ASoC: arizona: Allow specification of base for arizona_is_enabled_fll

In preparation for future improvements allow a base to be passed to
arizona_is_enabled_fll, this will allow it to be used to check the state
of the synchroniser path as well.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>