drm/amdgpu: use scheduler fault instead of reset work

Signal a fault to the scheduler on an illegal instruction or register
access violation instead of kicking of the reset handler directly.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>