regulator: core: fix debugfs creation regression

regulator: core: fix debugfs creation regression

regulator_get() may sometimes be called more than once for the same
consumer device, something which before commit dbe954d8f163 ("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: 2715bb11cfff ("regulator: core: Fix more error checking for debugfs_create_dir()")
Fixes: 08880713ceec ("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.org
Signed-off-by: Mark Brown <broonie@kernel.org>