ASoC: arizona: fix range of OPCLK_REF

The code was able to generate illegal OPCLK_REF values because the
reference frequency tables listed all values of SYSCLK instead of
valid values for OPCLK_REF clock. The maximum OPCLK_REF clock is
49.152MHz or 45.1584MHz.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>