According to the linux kernel 5.2 changelog
(https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2), the fix for the
DMCU firmware issue on raven1 platform is included in that release.

I went ahead and tested this and can confirm that I was able to boot without a
blank screen into my machine with kernel 5.2 without needing to use the
workaround.

I tested with:
1.) re-installed latest linux-firmware package
2.) installed kernel 5.2
3.) re-generated the initramfs
4.) booted into linux using kernel 5.2 and had no blank screen, dmesg output is
clean with no erros for amdgpu

Tested on:
HP HP ENVY x360 Convertible 15-bq1xx/83C6, BIOS F.21 04/29/2019

I guess if someone else can confirm my findings, maybe on different raven1
hardware, this ticket can be closed.