can: mcp251x: Fix regulators operation without CONFIG_REGULATOR
can: mcp251x: Fix regulators operation without CONFIG_REGULATOR

If CONFIG_REGULATOR is not set, devm_regulator_get() returns NULL,
so use IS_ERR_OR_NULL() macro for checks.

Signed-off-by: Alexander Shiyan <2d24902f83da69c248f5b0282406fefa25814305@mail.ru>
Signed-off-by: Marc Kleine-Budde <4a0ea1158d3cc63151119c05b1bff00c0bdbf421@pengutronix.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs