phy: phy-can-transceiver: Make devm_gpiod_get optional

In some cases the standby/enable gpio can be pulled low/high and would not
be connected to a gpio. The current driver implementation will return an
error in these cases. Therefore, make devm_gpiod_get optional.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20211102112120.23637-1-a-govindraju@ti.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>