drm/amdgpu: Move gfx flag in_suspend to adev

Move in_suspend flag to adev from gfx, so
can be used in other ip blocks, also keep
consistent with gpu_in_reset flag.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>