gsm 04.80: fix typo (256, not 265!)

This was introduced by me in commit
79599ba0eb7a9aeaeb9dfbbf4881f0633724a471

Thanks to Alexander Huemer for detecting it
diff --git a/include/osmocom/gsm/tlv.h b/include/osmocom/gsm/tlv.h
index 1e59cca..f659411 100644
--- a/include/osmocom/gsm/tlv.h
+++ b/include/osmocom/gsm/tlv.h
@@ -236,11 +236,11 @@
 };
 
 struct tlv_definition {
-	struct tlv_def def[265];
+	struct tlv_def def[256];
 };
 
 struct tlv_parsed {
-	struct tlv_p_entry lv[265];
+	struct tlv_p_entry lv[256];
 };
 
 extern struct tlv_definition tvlv_att_def;