Still having the same bug in kernel 5.0-rc4 and my raven_dmcu.bin also matches
to the previously attached bin file(sha256
a45972418d1c078afbd7884ffd58784954220759bc0d5464ce60165ffe1775bd).

However, in one of my tests I got it to work! So the time it worked I got lucky
I somehow misplaced raven_dmcu.bin so when I rebooted the kernel 5.0rc4 and
checked /lib/firmware/amdgpu/raven_dmcu.bin it wasn't there. As soon as I put
raven_dmcu.bin back in the folder /lib/firmware/amdgpu/ I got this bug again.
So the workaround is to delete raven_dmcu.bin from /lib/firmware/amdgpu for now
until they fix it. Laptop seems to work just fine. I don't know what that
firmware is for but it doesn't look like it's a required file for my HP x360
AMD Ryzen 2500U laptop