drm/amdgpu: Use init level for pending_reset flag

Drop pending_reset flag in gmc block. Instead use init level to
determine which type of init is preferred - in this case MINIMAL.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Acked-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Tested-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>