can: tcan4x5x: add max_raw_{read,write} of 256

The tcan4x5x chip support bulk read/write, but as the length field is only 8
bits wide, the maximum is 256. A length of 0 is treated as 256.
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Tested-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-14-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/tcan4x5x-regmap.c

@@ -67,6 +67,8 @@ static const struct regmap_bus tcan4x5x_bus = {
 	.read = tcan4x5x_regmap_read,
 	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
 	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.max_raw_read = 256,
+	.max_raw_write = 256,
 };
 
 int tcan4x5x_regmap_init(struct tcan4x5x_priv *priv)