can: tcan4x5x: fix power regulator retrieval during probe

Fixes the power regulator retrieval in tcan4x5x_can_probe() by ensuring
the regulator pointer is not set to NULL in the successful return from
devm_regulator_get_optional().

Fixes: 3814ca3a ("can: tcan4x5x: tcan4x5x_can_probe(): turn on the power before parsing the config")
Signed-off-by: Brett Werling <brett.werling@garmin.com>
Link: https://patch.msgid.link/20250612191825.3646364-1-brett.werling@garmin.com


Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>