can: tcan4x5x: tcan4x5x_bus: remove not needed read_flag_mask

With C99 initializers, all non mentioned members are initialzied to 0, so
remove not needed initialization of read_flag_mask.
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Tested-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-7-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

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

@@ -82,7 +82,6 @@ static const struct regmap_bus tcan4x5x_bus = {
 	.async_write = regmap_spi_async_write,
 	.async_alloc = regmap_spi_async_alloc,
 	.read = tcan4x5x_regmap_read,
-	.read_flag_mask = 0x00,
 	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
 	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
 };