drm/amdgpu: Move reset sem into reset_domain

drm/amdgpu: Move reset sem into reset_domain

We want single instance of reset sem across all
reset clients because in case of XGMI we should stop
access cross device MMIO because any of them could be
in a reset in the moment.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://www.spinics.net/lists/amd-gfx/msg74117.html