Write a 32-bit value of zero to disable GFXOFF and write a 32-bit
value of non-zero to enable GFXOFF.
Signed-off-by: NTom St Denis <tom.stdenis@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>