Revert "PM / OPP: Disable OPPs that aren't supported by the regulator"

This reverts commit a55a5305982d996a4db88c2525299edc836ebccf.

The _opp_supported_by_regulators used by debug part, and that missed
in current backport. so revert this commit to avoid a unused warning.

Reported-by:Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 6ec74b5..ed19c41 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -964,22 +964,6 @@
 	return opp;
 }
 
-static bool _opp_supported_by_regulators(struct dev_pm_opp *opp,
-					 struct device_opp *dev_opp)
-{
-	struct regulator *reg = dev_opp->regulator;
-
-	if (!IS_ERR(reg) &&
-	    !regulator_is_supported_voltage(reg, opp->u_volt_min,
-					    opp->u_volt_max)) {
-		pr_warn("%s: OPP minuV: %lu maxuV: %lu, not supported by regulator\n",
-			__func__, opp->u_volt_min, opp->u_volt_max);
-		return false;
-	}
-
-	return true;
-}
-
 static int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
 		    struct device_opp *dev_opp)
 {