regulator: Fix regression due to NULL constraints check

The commit [39f802d6b6d9: 'regulator: Build sysfs entries with static
attribute groups'] converted the sysfs entry creation to static
attribute groups, but this resulted in a regression due to the NULL
check of rdev->constraints.  At the point where the device is
registered, rdev->constraints isn't set, so the attributes depending
on it are missing.

We may fix it by shuffling the code order in regulator_register(), but
a quicker fix is to just remove this NULL check.  rdev->constraints is
in anyway always set to non-NULL in set_machine_constraints(), thus
the check there is basically superfluous.

Fixes: 39f802d6b6d9 ('regulator: Build sysfs entries with static attribute groups')
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reportded-by: Steve Twiss <stwiss.opensource@diasemi.com>
Tested-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -3444,13 +3444,6 @@ static umode_t regulator_attr_is_visible(struct kobject *kobj,
 	if (attr == &dev_attr_requested_microamps.attr)
 		return rdev->desc->type == REGULATOR_CURRENT ? mode : 0;
 
-	/* all the other attributes exist to support constraints;
-	 * don't show them if there are no constraints, or if the
-	 * relevant supporting methods are missing.
-	 */
-	if (!rdev->constraints)
-		return 0;
-
 	/* constraints need specific supporting methods */
 	if (attr == &dev_attr_min_microvolts.attr ||
 	    attr == &dev_attr_max_microvolts.attr)