iio: frequency: ad9832: simplify bitwise math

Refactor the ad9832_calc_freqreg by removing the redundant u64 casts
and 1L bitwise left shift and replacing the multiplication by a bit
shift, as multiplying integers by a power of two is identical to a
bitwise left shift.

Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: cjd8

drivers/staging/iio/frequency/ad9832.c

@@ -117,8 +117,8 @@ struct ad9832_state {
 
 static unsigned long ad9832_calc_freqreg(unsigned long mclk, unsigned long fout)
 {
-	unsigned long long freqreg = (u64)fout *
-				     (u64)((u64)1L << AD9832_FREQ_BITS);
+	u64 freqreg = (u64)fout << AD9832_FREQ_BITS;
+
 	do_div(freqreg, mclk);
 	return freqreg;
 }