chan_sip: Fix small behavioral change accidentally introduced in r369750

When removing the warning for AST_CONTROL_FLASH from sip_indicate, I also
inadvertently changed the return value, which would likely make the indication
not be sent in audio. This fixes that while still removing the warning message.
........

Merged revisions 369792 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@369793 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -7050,7 +7050,8 @@ static int sip_indicate(struct ast_channel *ast, int condition, const void *data
 		break;
 	case AST_CONTROL_UPDATE_RTP_PEER: /* Absorb this since it is handled by the bridge */
 		break;
-	case AST_CONTROL_FLASH: /* Absorb this since it is irrelevant to SIP. */
+	case AST_CONTROL_FLASH: /* We don't currently handle AST_CONTROL_FLASH here, but it is expected, so we don't need to warn either. */
+		res = -1;
 		break;
 	case -1:
 		res = -1;