regulator: check that dummy regulator has been probed before using it

regulator: check that dummy regulator has been probed before using it

commit 2c7a50bec4958f1d1c84d19cde518d0e96a676fd upstream.

Due to asynchronous driver probing there is a chance that the dummy
regulator hasn't already been probed when first accessing it.

Cc: stable@vger.kernel.org
Signed-off-by: Christian Eggers <ceggers@arri.de>
Link: https://patch.msgid.link/20250313103051.32430-3-ceggers@arri.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>