spi: imx: use true,false for bool variable

Fixes coccicheck warning:

drivers/spi/spi-imx.c:1233:2-17: WARNING: Assignment of 0/1 to bool variable
drivers/spi/spi-imx.c:1235:2-17: WARNING: Assignment of 0/1 to bool variable

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Link: https://lore.kernel.org/r/1577159526-33689-3-git-send-email-zhengbin13@huawei.com


Signed-off-by: Mark Brown <broonie@kernel.org>