drm/amdgpu: Enable GFXOFF for Compute on GFX11

On GFX version 11, GFXOFF was disabled due to a MES KIQ firmware
issue, which has since been fixed after version 64.
This patch only re-enables GFXOFF for GFX version 11 if the GPU's
MES KIQ firmware version is newer than version 64.

V2: Keep GFXOFF disabled on GFX11 if MES KIQ is below version 64.
V3: Add parentheses to avoid GCC warning for parentheses:
"suggest parentheses around comparison in operand of ‘&’"
V4: Remove "V3" from commit title
V5: Change commit description and insert 'Acked-by'

Signed-off-by: Ori Messinger <Ori.Messinger@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>