regmap: use IS_ALIGNED instead of % to improve the

 performance

The stride value should always equal to 2^n, so we can use bit
rotation instead of % to improve the performance.

Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: UpInTheAir <upintheair.skyhigh@gmail.com>