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: NHulk Robot <hulkci@huawei.com>
Signed-off-by: Nzhengbin <zhengbin13@huawei.com>
Link: https://lore.kernel.org/r/1577159526-33689-3-git-send-email-zhengbin13@huawei.comSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-imx.c

@@ -1230,9 +1230,9 @@ static int spi_imx_setupxfer(struct spi_device *spi,
 	}
 
 	if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
-		spi_imx->usedma = 1;
+		spi_imx->usedma = true;
 	else
-		spi_imx->usedma = 0;
+		spi_imx->usedma = false;
 
 	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode) {
 		spi_imx->rx = mx53_ecspi_rx_slave;