can: sja1000: fix size of OCR_MODE_MASK define

bitfield mode in ocr register has only 2 bits not 3, so correct
the OCR_MODE_MASK define.

Signed-off-by: Heiko Schocher <hs@denx.de>
Link: https://lore.kernel.org/all/20221123071636.2407823-1-hs@denx.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>