regulator: core: fix debugfs creation regression

regulator_get() may sometimes be called more than once for the same
consumer device, something which before commit dbe954d8 ("regulator:
core: Avoid debugfs: Directory ...  already present! error") resulted in
errors being logged.

A couple of recent commits broke the handling of such cases so that
attributes are now erroneously created in the debugfs root directory the
second time a regulator is requested and the log is filled with errors
like:

	debugfs: File 'uA_load' in directory '/' already present!
	debugfs: File 'min_uV' in directory '/' already present!
	debugfs: File 'max_uV' in directory '/' already present!
	debugfs: File 'constraint_flags' in directory '/' already present!

on any further calls.

Fixes: 2715bb11 ("regulator: core: Fix more error checking for debugfs_create_dir()")
Fixes: 08880713 ("regulator: core: Streamline debugfs operations")
Cc: stable@vger.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240509133304.8883-1-johan+linaro@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1911,11 +1911,15 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 		}
 	}
 
-	if (err != -EEXIST)
+	if (err != -EEXIST) {
 		regulator->debugfs = debugfs_create_dir(supply_name, rdev->debugfs);
-	if (IS_ERR(regulator->debugfs))
+		if (IS_ERR(regulator->debugfs)) {
 			rdev_dbg(rdev, "Failed to create debugfs directory\n");
+			regulator->debugfs = NULL;
+		}
+	}
 
+	if (regulator->debugfs) {
 		debugfs_create_u32("uA_load", 0444, regulator->debugfs,
 				   &regulator->uA_load);
 		debugfs_create_u32("min_uV", 0444, regulator->debugfs,
@@ -1924,6 +1928,7 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 				   &regulator->voltage[PM_SUSPEND_ON].max_uV);
 		debugfs_create_file("constraint_flags", 0444, regulator->debugfs,
 				    regulator, &constraint_flags_fops);
+	}
 
 	/*
 	 * Check now if the regulator is an always on regulator - if