drm/amdgpu: Do not program PF-only regs in hdp_v4_0.c under SRIOV (v2)

The following regs can only be programmed by the PF:
HDP_MISC_CNTL
HDP_NONSURFACE_BASE
HDP_NONSURFACE_BASE_HI

v2: update commit message

Signed-off-by: Victor Lu <victorchengchi.lu@amd.com>
Reviewed-by: Samir Dhume <samir.dhume@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>