[SGSN] Some IEs in ATTACH REQUEST can be longer in 24.008

The original length checks were based on 04.08, but 24.008 allows
longer IEs.
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index e071802..817092e 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -626,7 +626,7 @@
 	/* MS network capability 10.5.5.12 */
 	msnc_len = *cur++;
 	msnc = cur;
-	if (msnc_len > 2)
+	if (msnc_len > 8)
 		goto err_inval;
 	cur += msnc_len;
 
@@ -657,6 +657,8 @@
 	/* MS Radio Access Capability 10.5.5.12a */
 	ms_ra_acc_cap_len = *cur++;
 	ms_ra_acc_cap = cur;
+	if (ms_ra_acc_cap_len > 51)
+		goto err_inval;
 
 	/* Optional: Old P-TMSI Signature, Requested READY timer, TMSI Status */