regulator: core: Make error messages more informative

The same error print exists 4 times in the regulator core

	<rdev>: operation not allowed

Unfortunately, seeing this in the dmesg is not very informative.
Add what type of operation is not allowed to the message so that
these errors are unique, hopefully pointing developers in the
right direction

	<rdev>: drms operation not allowed
	<rdev>: voltage operation not allowed
	<rdev>: current operation not allowed
	<rdev>: mode operation not allowed
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -180,7 +180,7 @@ static int regulator_check_voltage(struct regulator_dev *rdev,
 		return -ENODEV;
 	}
 	if (!(rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_VOLTAGE)) {
-		rdev_err(rdev, "operation not allowed\n");
+		rdev_err(rdev, "voltage operation not allowed\n");
 		return -EPERM;
 	}
 
@@ -240,7 +240,7 @@ static int regulator_check_current_limit(struct regulator_dev *rdev,
 		return -ENODEV;
 	}
 	if (!(rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_CURRENT)) {
-		rdev_err(rdev, "operation not allowed\n");
+		rdev_err(rdev, "current operation not allowed\n");
 		return -EPERM;
 	}
 
@@ -277,7 +277,7 @@ static int regulator_mode_constrain(struct regulator_dev *rdev, int *mode)
 		return -ENODEV;
 	}
 	if (!(rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_MODE)) {
-		rdev_err(rdev, "operation not allowed\n");
+		rdev_err(rdev, "mode operation not allowed\n");
 		return -EPERM;
 	}
 
@@ -301,7 +301,7 @@ static int regulator_check_drms(struct regulator_dev *rdev)
 		return -ENODEV;
 	}
 	if (!(rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_DRMS)) {
-		rdev_dbg(rdev, "operation not allowed\n");
+		rdev_dbg(rdev, "drms operation not allowed\n");
 		return -EPERM;
 	}
 	return 0;