ath5k: avoid unneeded calibration error messages

Don't generate calibration errors messages when not needed.
Signed-off-by: NFabio Rossi <rossi.f@inwind.it>
Acked-by: NBruno Randolf <br1@einfach.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/phy.c

@@ -1377,7 +1377,7 @@ ath5k_hw_rf511x_iq_calibrate(struct ath5k_hw *ah)
 
 	/* protect against divide by 0 and loss of sign bits */
 	if (i_coffd == 0 || q_coffd < 2)
-		return -1;
+		return 0;
 
 	i_coff = (-iq_corr) / i_coffd;
 	i_coff = clamp(i_coff, -32, 31); /* signed 6 bit */