Add RW mtype introduced for arcturus.

v2:
* Don't add probe-invalidation bit from UAPI
* Don't add unused AMDGPU_MTYPE_ definitions
Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Shaoyun Liu <Shaoyun.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>