amdgpu/pp: slim down the pwr virus tables.

This is what I'd call slightly overengineered, we waste 40k on
storing a value that is write or end, when we could just use the
register value to denote end.

Remove the virus command parameter, and save
   text	   data	    bss	    dec	    hex	filename
1412724	  17982	   1008	1431714	 15d8a2	../drm-next-build/drivers/gpu/drm/amd/amdgpu/amdgpu.o
1331332	  17982	   1008	1350322	 149ab2	../drm-next-build/drivers/gpu/drm/amd/amdgpu/amdgpu.o

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>