regulator: fixed: use dev_err_probe for gpio

Instead of returning the the PTR_ERR directly, use dev_err_probe which
will also correctly set the deferred probe reason in
/sys/kernel/debug/deferred_devices, making it easier to debug missing
devices on the system.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
Link: https://lore.kernel.org/r/20210616125331.153414-1-r.czerwinski@pengutronix.de


Signed-off-by: Mark Brown <broonie@kernel.org>