dccp ccid-3: replace incorrect BUG_ON

This replaces an unjustified BUG_ON(), which could get triggered under normal
conditions: X_calc can be 0 when p > 0. X would in this case be set to the
minimum, s/t_mbi. Its replacement avoids t_ipi = 0 (unbounded sending rate).

Thanks to Jordi, Victor and Xavier who reported this.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.uk>

net/dccp/ccids/ccid3.c

@@ -98,6 +98,7 @@ static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc)
 {
 	hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x);
 
+	DCCP_BUG_ON(hc->tx_t_ipi == 0);
 	ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi,
 		       hc->tx_s, (unsigned)(hc->tx_x >> 6));
 }
@@ -236,8 +237,6 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
 		 *
 		 *  Note that X_recv is scaled by 2^6 while X_calc is not
 		 */
-		BUG_ON(hc->tx_p && !hc->tx_x_calc);
-
 		if (hc->tx_x_calc > (hc->tx_x_recv >> 5))
 			hc->tx_x_recv =
 				max(hc->tx_x_recv / 2,