regulator: pfuze100: add MODULE_LICENSE() in pfuze100 driver

Fix building error on x86_64 and i386:
WARNING: modpost: missing MODULE_LICENSE() in
drivers/regulator/pfuze100-regulator.o

Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>