I'm getting a Backtrace on boot.
Something about kobject_add_internal, the issue is often happened after kernel update.  

Steps to reproduce the issue:

Build raspberrypi image with lastest dunfell branch.
Boot the image on the pi
[    1.511915] simple-framebuffer 1e513000.framebuffer: format=a8r8g8b8, mode=1824x984x32, linelength=7296
[    1.548182] Console: switching to colour frame buffer device 228x61
[    1.580552] simple-framebuffer 1e513000.framebuffer: fb0: simplefb registered!
[    1.581567] sysfs: cannot create duplicate filename '/devices/platform/1e513000.framebuffer'
[    1.581908] CPU: 0 PID: 1 Comm: swapper Not tainted 5.4.59 #1
[    1.582125] Hardware name: BCM2835
[    1.582269] Backtrace: 
[    1.582419] [<c00157dc>] (dump_backtrace) from [<c0015b28>] (show_stack+0x20/0x24)
[    1.582706]  r7:00000000 r6:cb5d87a0 r5:cb51e5a0 r4:cb47b000
[    1.582942] [<c0015b08>] (show_stack) from [<c07bc1b4>] (dump_stack+0x20/0x28)
[    1.583231] [<c07bc194>] (dump_stack) from [<c0252018>] (sysfs_warn_dup+0x60/0x74)
[    1.583519] [<c0251fb8>] (sysfs_warn_dup) from [<c025216c>] (sysfs_create_dir_ns+0xec/0x10c)
[    1.583820]  r7:00000000 r6:cb51e5a0 r5:ffffffef r4:cb5e2a10
[    1.584063] [<c0252080>] (sysfs_create_dir_ns) from [<c07c14e8>] (kobject_add_internal+0x90/0x308)
[    1.584385]  r6:c1039928 r5:c1039928 r4:cb5e2a10
[    1.584586] [<c07c1458>] (kobject_add_internal) from [<c07c1c98>] (kobject_add+0x60/0xc4)
[    1.584885]  r9:c0ac282c r8:c1078000 r7:00000000 r6:c1039928 r5:cb5e2a10 r4:00000000
[    1.585203] [<c07c1c38>] (kobject_add) from [<c0523a78>] (device_add+0x100/0x61c)
[    1.585474]  r3:00000000 r2:00000000
[    1.585738]  r6:c1039928 r5:dbf62b9c r4:cb5e2a10
[    1.585964] [<c0523978>] (device_add) from [<c0648c10>] (of_device_add+0x40/0x48)
[    1.586253]  r8:c1078000 r7:00000000 r6:00000000 r5:dbf62b9c r4:cb5e2a00
[    1.586514] [<c0648bd0>] (of_device_add) from [<c0649398>] (of_platform_device_create_pdata+0xb4/0xfc)
[    1.586857] [<c06492e4>] (of_platform_device_create_pdata) from [<c0649400>] (of_platform_device_create+0x20/0x24)
[    1.587221]  r7:c09c31e0 r6:c111e8f0 r5:00000000 r4:dbf62b9c
[    1.587462] [<c06493e0>] (of_platform_device_create) from [<c0aa366c>] (simplefb_init+0x74/0x9c)
[    1.587794] [<c0aa35f8>] (simplefb_init) from [<c000ade0>] (do_one_initcall+0x50/0x1d4)
[    1.588089]  r7:00000000 r6:c1078000 r5:c0ac284c r4:c0aa35f8
[    1.598984] [<c000ad90>] (do_one_initcall) from [<c0a731c0>] (kernel_init_freeable+0x130/0x1f4)
[    1.609929]  r7:c0a6f4a0 r6:c1078000 r5:c0ac284c r4:c0aeb94c
[    1.620971] [<c0a73090>] (kernel_init_freeable) from [<c07d3af0>] (kernel_init+0x18/0xfc)
[    1.631962]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c07d3ad8
[    1.642924]  r4:00000000
[    1.653955] [<c07d3ad8>] (kernel_init) from [<c00090ac>] (ret_from_fork+0x14/0x28)
[    1.664988] Exception stack(0xcb4cbfb0 to 0xcb4cbff8)
[    1.675936] bfa0:                                     00000000 00000000 00000000 00000000
[    1.687241] bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    1.698351] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    1.709317]  r5:c07d3ad8 r4:00000000
[    1.720413] kobject_add_internal failed for 1e513000.framebuffer with -EEXIST, don't try to register things with the same name in the same directory.