We need some different logic for dGPUs and the APU path
can be simplified because there are some methods which
are never used on APUs.  This also fixes a regression
on some older APUs causing the driver to fetch the
unpatched ROM image rather than the patched image.

Fixes: 9c081c11 ("drm/amdgpu: Reorder to read EFI exported ROM first")
Reviewed-by: George Zhang <George.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>