Fixes for RHEL9 kernel backports

[cyqsimon]

Closes #7; closes #13.

RHEL's kernels have backported changes from newer versions, so additional conditional compilation checks using RHEL-specific macros are necessary.

I originally submitted them to upstream at google#29 and google#37. But on recommendation from a SUSE maintainer, I think it's a better idea to add those distro-specific patches here.

[cyqsimon]

There very well may be similar backports happening in RHEL8, but I don't own a RHEL8 system with the accelerator hardware. On second thought, I don't actually need the hardware to test module compile.

Regardless, these patches shouldn't harm them in any way. These problems (if they exist) can be fixed later on when people report them.

[weegeekps]

Will this be merged? While manually applying this patch has gotten my PCIe Coral working on my AlmaLinux 9 server, it'd be appreciated to not have to manually apply it in the future.