I tested this yesterday with kernel 5.1.8 and if the file raven_dmcu.bin is
present in the /lib/firmware/amdgpu/ folder when you are updating the kernel
(or manually rebuilding the initramfs), the computer will boot with a blank
screen next time.

There are 2 pieces to this. The linux-firmware package provides the binary
files (i.e. the raven_dmcu.bin) so every time this package gets updated, you
should rename/move the file and rebuild the initramfs. The linux-firmware
updates are not as frequent as the kernel updates so if you do the workaround,
you might go through several kernel updates without issues, but once
linux-firmware updates, you have to repeat the workaround...

All the patch in the kernel will do is to ignore the raven_dmcu.bin file
automatically (for raven 1 cpus) when building the initramfs so you don't have
to rename/move it every time linux-firmware updates.