osmo-auc-gen: Permit specifying the SQN in hex (0x12345) format

Use base '0' of strtoul to permit both decimal and hexadecimal input
to the SQN parameter.  Some other tools represent the SQN as hex,
so this avoids having to use some external tool to convert and allows
you to copy+paste it to the osmo-auc-gen command line.

Change-Id: I67c6341a989de433451994b824e12afd0c26cb8a
diff --git a/utils/osmo-auc-gen.c b/utils/osmo-auc-gen.c
index 65cfa31..eb6c65b 100644
--- a/utils/osmo-auc-gen.c
+++ b/utils/osmo-auc-gen.c
@@ -207,7 +207,7 @@
 				fprintf(stderr, "Only UMTS has SQN\n");
 				exit(2);
 			}
-			sqn = strtoull(optarg, 0, 10);
+			sqn = strtoull(optarg, 0, 0);
 			sqn_is_set = 1;
 			break;
 		case 'i':