spi: spi-fsl-lpspi: use min_t() to improve code

Use min_t() to reduce the code in fsl_lpspi_setup_transfer() and
improve its readability.

Signed-off-by: Qianfeng Rong <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Reviewed-by: Frank Li <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-fsl-lpspi.c

···
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/types.h>
+#include <linux/minmax.h>
 
 #define DRIVER_NAME "fsl_lpspi"
 
···
 		fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
 	}
 
-	if (t->len <= fsl_lpspi->txfifosize)
-		fsl_lpspi->watermark = t->len;
-	else
-		fsl_lpspi->watermark = fsl_lpspi->txfifosize;
+	fsl_lpspi->watermark = min_t(typeof(fsl_lpspi->watermark),
+				     fsl_lpspi->txfifosize,
+				     t->len);
 
 	if (fsl_lpspi_can_dma(controller, spi, t))
 		fsl_lpspi->usedma = true;