Revert "drm/amdgpu: force exit gfxoff on sdma resume for rmb s0ix"

This reverts commit e5d59cfa.

This is no longer needed since we no longer suspend SDMA during
S0ix.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>