graphics/drm-devel-kmod: fix package

Fix packaging of graphics/drm-devel-kmod, the amdkfd module has been
disabled, and I missed this last night. Remove it from the pkg-plist by
commenting it out for all architectures for now.
This is a stop gap measure to get the port to package, until I can touch
base with johalun and jmd about how to handle this permanently.

MFH: 2019Q2 (implicit, drm-drivers blanket)
Sponsored by: B3 Init