spi: spi-fsl-lpspi: Set correct chip-select polarity bit

The driver currently supports multiple chip-selects, but only sets the
polarity for the first one (CS 0). Fix it by setting the PCSPOL bit for
the desired chip-select.

Fixes: 5314987 ("spi: imx: add lpspi bus driver")
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250828-james-nxp-lpspi-v2-2-6262b9aa9be4@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Larisa Grigore

drivers/spi/spi-fsl-lpspi.c

@@ -5,6 +5,7 @@
 // Copyright 2016 Freescale Semiconductor, Inc.
 // Copyright 2018, 2023, 2025 NXP
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
@@ -70,7 +71,7 @@
 #define DER_TDDE	BIT(0)
 #define CFGR1_PCSCFG	BIT(27)
 #define CFGR1_PINCFG	(BIT(24)|BIT(25))
-#define CFGR1_PCSPOL	BIT(8)
+#define CFGR1_PCSPOL_MASK	GENMASK(11, 8)
 #define CFGR1_NOSTALL	BIT(3)
 #define CFGR1_HOST	BIT(0)
 #define FSR_TXCOUNT	(0xFF)
@@ -423,7 +424,9 @@ static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
 	else
 		temp = CFGR1_PINCFG;
 	if (fsl_lpspi->config.mode & SPI_CS_HIGH)
-		temp |= CFGR1_PCSPOL;
+		temp |= FIELD_PREP(CFGR1_PCSPOL_MASK,
+				   BIT(fsl_lpspi->config.chip_select));
+
 	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
 
 	temp = readl(fsl_lpspi->base + IMX7ULP_CR);