drm/amdgpu/sdma5: init engine reset mutex

Missing the mutex init.

Fixes: e56d4bf ("drm/amdgpu/: drm/amdgpu: Register the new sdma function pointers for sdma_v5_0")
Reviewed-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3f4caf0)

Author: alexdeucher

drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c

@@ -1399,6 +1399,7 @@ static int sdma_v5_0_sw_init(struct amdgpu_ip_block *ip_block)
 		return r;
 
 	for (i = 0; i < adev->sdma.num_instances; i++) {
+		mutex_init(&adev->sdma.instance[i].engine_reset_mutex);
 		adev->sdma.instance[i].funcs = &sdma_v5_0_sdma_funcs;
 		ring = &adev->sdma.instance[i].ring;
 		ring->ring_obj = NULL;