drm/amdgpu: Fix SDMA hang in prt mode v2

drm/amdgpu: Fix SDMA hang in prt mode v2

Fix SDMA hang in prt mode, clear XNACK_WATERMARK in reg SDMA0_UTCL1_WATERMK to avoid the issue

Affected ASICs: VEGA10 VEGA12 RV1 RV2

v2: add reg clear for SDMA1

Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Tested-by: Yukun Li <yukun1.li@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>