Direct IB pool is used for vce/vcn IB extra msg too. Increase its size
to AMDGPU_IB_POOL_SIZE.

v2: Squash in unused variable removal
Signed-off-by: Nxinhui pan <xinhui.pan@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>