gtpie_{encaps,encaps2}(): RAI is a fixe 6-byte length field, not 8 bytes

gtpie_decaps() always had this right, but the encapsulation functions
treated it as 8-byte fixed length IE.

I hope we had a chance to convert all of this to the normal libosmogsm
tlv_parser one day.  This would have one description table for all TLV
types which then is used from encoder and decoder.

Change-Id: I48471f2735511806ac424b5ffc1929e85bb156f3
diff --git a/gtp/gtpie.c b/gtp/gtpie.c
index c4eabf8..fa21ab2 100644
--- a/gtp/gtpie.c
+++ b/gtp/gtpie.c
@@ -652,11 +652,13 @@
 			case GTPIE_TEI_DII:	/* TV GTPIE types with value length 5 */
 				iesize = 6;
 				break;
+			case GTPIE_RAI:		/* TV GTPIE types with value length 6 */
+				iesize = 7;
+				break;
 			case GTPIE_RAB_CONTEXT:	/* TV GTPIE types with value length 7 */
 				iesize = 8;
 				break;
 			case GTPIE_IMSI:	/* TV GTPIE types with value length 8 */
-			case GTPIE_RAI:
 				iesize = 9;
 				break;
 			case GTPIE_AUTH_TRIPLET:	/* TV GTPIE types with value length 28 */
@@ -827,11 +829,13 @@
 				case GTPIE_TEI_DII:	/* TV GTPIE types with value length 5 */
 					iesize = 6;
 					break;
+				case GTPIE_RAI:		/* TV GTPIE types with value length 6 */
+					iesize = 7;
+					break;
 				case GTPIE_RAB_CONTEXT:	/* TV GTPIE types with value length 7 */
 					iesize = 8;
 					break;
 				case GTPIE_IMSI:	/* TV GTPIE types with value length 8 */
-				case GTPIE_RAI:
 					iesize = 9;
 					break;
 				case GTPIE_AUTH_TRIPLET:	/* TV GTPIE types with value length 28 */