rtp_engine: Remove the double assigned RTP payload ID of H.263+.

Mantis-3709 (Commit 68ff3c3, Asterisk 1.2) added support for the video format
H.263+. For this, the RTP payload ID 103 got assigned statically. Commit f1aadc8
assigned another payload ID 98 for this format in Asterisk 1.6.

Change-Id: I90e35b158487f8f1f8187da6241b54cd3b74e667

main/rtp_engine.c

@@ -3366,7 +3366,7 @@ int ast_rtp_engine_init(void)
 	 */
 	add_static_payload(96, ast_format_slin192, 0);
 	add_static_payload(97, ast_format_ilbc, 0);
-	add_static_payload(98, ast_format_h263p, 0);
+
 	add_static_payload(99, ast_format_h264, 0);
 	add_static_payload(100, ast_format_vp8, 0);
 	add_static_payload(101, NULL, AST_RTP_DTMF);