ath9k: remove ath9k_mod_tsf64_tu

Remove ath9k_mod_tsf64_tu() function while we could
use div_u64_rem() function.
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath9k/common-beacon.c

@@ -18,30 +18,16 @@
 
 #define FUDGE 2
 
-/* Calculate the modulo of a 64 bit TSF snapshot with a TU divisor */
-static u32 ath9k_mod_tsf64_tu(u64 tsf, u32 div_tu)
-{
-	u32 tsf_mod, tsf_hi, tsf_lo, mod_hi, mod_lo;
-
-	tsf_mod = tsf & (BIT(10) - 1);
-	tsf_hi = tsf >> 32;
-	tsf_lo = ((u32) tsf) >> 10;
-
-	mod_hi = tsf_hi % div_tu;
-	mod_lo = ((mod_hi << 22) + tsf_lo) % div_tu;
-
-	return (mod_lo << 10) | tsf_mod;
-}
-
 static u32 ath9k_get_next_tbtt(struct ath_hw *ah, u64 tsf,
 			       unsigned int interval)
 {
-	unsigned int offset;
+	unsigned int offset, divisor;
 
 	tsf += TU_TO_USEC(FUDGE + ah->config.sw_beacon_response_time);
-	offset = ath9k_mod_tsf64_tu(tsf, interval);
+	divisor = TU_TO_USEC(interval);
+	div_u64_rem(tsf, divisor, &offset);
 
-	return (u32) tsf + TU_TO_USEC(interval) - offset;
+	return (u32) tsf + divisor - offset;
 }
 
 /*