regulator: s2mps11: Simplify expression used in BUILD_BUG_ON

Following BUILD_BUG_ON using a variable fails for some of the compilers
and optimization levels (reported for gcc 4.9):
	var = ARRAY_SIZE(s2mps15_regulators);
	BUILD_BUG_ON(S2MPS_REGULATOR_MAX < var);
Fix this by using ARRAY_SIZE directly.

Additionally add missing BUILD_BUG_ON check for S2MPS15 device (the
check ensures that internal arrays are big enough to hold data for all
of regulators on all devices).

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>