regulator: db8500-prcmu: Remove unused declaration power_state_active_is_enabled()

Commit 38e96838 ("regulators/db8500: split off shared dbx500 code")
removed this but not its declaration.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20230818124227.15084-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/db8500-prcmu.h

@@ -35,10 +35,4 @@ enum db8500_regulator_id {
 	DB8500_NUM_REGULATORS
 };
 
-/*
- * Exported interface for CPUIdle only. This function is called with all
- * interrupts turned off.
- */
-int power_state_active_is_enabled(void);
-
 #endif