ASoC: nau8825: fix bug in FLL parameter

In the FLL parameter calculation, the FVCO should choose the maximum one.
The patch is to fix the bug about the wrong FVCO chosen.

Signed-off-by: John Hsu <KCHSU0@nuvoton.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org