ASoC: arizona: Fixed a bug in FLL fractional calculation

Previously arizona_calc_fll() was checking if the target frequency is
exactly divisible by reference frequency, but should have been product
of the ratio and the reference frequency.

Also scale down the Lamba and Theta coefficients be under 16-bits in
order to match the registers.

Signed-off-by: Ryo Tsutsui <ryo.tsutsui@wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org