linux-phytec-fsl

MLK-12173 regulator: pfuze100: add .is_enable() for pfuze100_swb_regulator_ops

If is_enabled() is not defined in its ops, regulator core will assume
this regulator is already enabled, then we never can really enable it
after disabled.

Signed-off-by: Li Jun <jun.li@nxp.com>