can: tcan4x5x: tcan4x5x_parse_config(): Disable the INH pin device-state GPIO is unavailable

If the device state GPIO is not connected to the host then disable the
INH output from the TCAN device per section 8.3.5 of the data sheet.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>