drivers: spi: spi_mcux_ecspi: Ignore chip select channel with cs-gpios

The internal chip selects are limited to 4, however when using GPIOS
does not pose this limitation.
Also set internal channel to 0 if GPIOS are used.

Signed-off-by: Pieter De Gendt <[email protected]>
(cherry picked from commit 7250e98)

Author: pdgendt

drivers/spi/spi_mcux_ecspi.c

@@ -162,7 +162,7 @@ static int spi_mcux_configure(const struct device *dev,
 		return -ENOTSUP;
 	}
 
-	if (spi_cfg->slave > kECSPI_Channel3) {
+	if (!spi_cs_is_gpio(spi_cfg) && spi_cfg->slave > kECSPI_Channel3) {
 		LOG_ERR("Slave %d is greater than %d", spi_cfg->slave, kECSPI_Channel3);
 		return -EINVAL;
 	}
@@ -180,7 +180,8 @@ static int spi_mcux_configure(const struct device *dev,
 
 	ECSPI_MasterGetDefaultConfig(&master_config);
 
-	master_config.channel = (ecspi_channel_source_t)spi_cfg->slave;
+	master_config.channel =
+		spi_cs_is_gpio(spi_cfg) ? kECSPI_Channel0 : (ecspi_channel_source_t)spi_cfg->slave;
 	master_config.channelConfig.polarity =
 		(SPI_MODE_GET(spi_cfg->operation) & SPI_MODE_CPOL)
 		? kECSPI_PolarityActiveLow