gpu: host1x: Forbid RESTART opcode in the firewall

The RESTART opcode terminates the gather and restarts the CDMA fetching
from a specified word << 2 relative to the CDMA start address. That
shouldn't be allowed to be done by userspace.
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Reviewed-by: NErik Faye-Lund <kusmabite@gmail.com>
Reviewed-by: NMikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

drivers/gpu/host1x/job.c

@@ -495,7 +495,6 @@ static int validate(struct host1x_firewall *fw, struct host1x_job_gather *g)
 				goto out;
 			break;
 		case 4:
-		case 5:
 		case 14:
 			break;
 		default: