regulator: core: silence warning: "VDD1: ramp_delay not set"

commit 73e705bf ("regulator: core: Add set_voltage_time op")

introduced a new rdev_warn() if the ramp_delay is 0.

Apparently, on omap3/twl4030 platforms with dynamic voltage
management this results in non-ending spurious messages like

[  511.143066] VDD1: ramp_delay not set
[  511.662322] VDD1: ramp_delay not set
[  513.903625] VDD1: ramp_delay not set
[  514.222198] VDD1: ramp_delay not set
[  517.062835] VDD1: ramp_delay not set
[  517.382568] VDD1: ramp_delay not set
[  520.142791] VDD1: ramp_delay not set
[  520.502593] VDD1: ramp_delay not set
[  523.062896] VDD1: ramp_delay not set
[  523.362701] VDD1: ramp_delay not set
[  526.143035] VDD1: ramp_delay not set

I have observed this on GTA04 while it is reported to occur on
N900 as well: https://bugzilla.kernel.org/show_bug.cgi?id=178371

This patch makes the warning appear only in debugging mode.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -2754,7 +2754,7 @@ static int _regulator_set_voltage_time(struct regulator_dev *rdev,
 		ramp_delay = rdev->desc->ramp_delay;
 
 	if (ramp_delay == 0) {
-		rdev_warn(rdev, "ramp_delay not set\n");
+		rdev_dbg(rdev, "ramp_delay not set\n");
 		return 0;
 	}