regmap: Check stride of register patch as we register it

Currently, we check the registers in the patch are aligned to the
register stride everytime we sync the cache and the first time the patch
is written out is unchecked.

This patch checks the register patch when we first register it so the
first writes are no longer unchecked and then doesn't check on
subsequent syncs as the patch will be unchanged.

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