opal-gard: Add support for new PVR POWER9P.

Enable a new PVR for gard tool to work on another p9 variant. Makes op-test
as well happy.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
[oliver: s/Axone/axone/]
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

external/gard/gard.c

@@ -153,6 +153,7 @@ static void guess_chip_gen(void)
 		return;
 
 	case 0x004e: /* nimbus */
+	case 0x004f: /* axone */
 		set_chip_gen(p9_chip_units);
 		return;