regulator: rohm-generic: iniline stub function

The function rohm_regulator_set_voltage_sel_restricted() has a stub
implementation. Linux-next testing spot following:

include/linux/mfd/rohm-generic.h:93:12: error:
'rohm_regulator_set_voltage_sel_restricted' defined but not used

Fix this by inlining the stub.

Fixes: 8b6e8855 ("regulator: rohm-regulator: add helper for restricted voltage setting")
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/YZzEP3S7U15bTDAI@fedoraSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/mfd/rohm-generic.h

@@ -90,7 +90,8 @@ static inline int rohm_regulator_set_dvs_levels(const struct rohm_dvs_config *dv
 {
 	return 0;
 }
-static int rohm_regulator_set_voltage_sel_restricted(struct regulator_dev *rdev,
+
+static inline int rohm_regulator_set_voltage_sel_restricted(struct regulator_dev *rdev,
 						     unsigned int sel)
 {
 	return 0;