regulator: Fix resume from suspend to idle

When resuming from idle with the new suspend mode configuration support
we go through the resume callbacks with a state of PM_SUSPEND_TO_IDLE
which we don't have regulator constraints for, causing an error:

    dpm_run_callback(): regulator_resume_early+0x0/0x64 returns -22
    PM: Device regulator.0 failed to resume early: error -22

Avoid this and similar errors by treating missing constraints as a noop.

See also commit 57a0dd18 ("regulator: Fix suspend to idle"),
which fixed the suspend part.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -4310,7 +4310,7 @@ static int _regulator_resume_early(struct device *dev, void *data)
 
 	rstate = regulator_get_suspend_state(rdev, *state);
 	if (rstate == NULL)
-		return -EINVAL;
+		return 0;
 
 	mutex_lock(&rdev->mutex);