spi: imx: Take in account bits per word instead of assuming 8-bits

The IMX spi driver has a hardcoded 8, breaking the driver for word
lengths other than 8.

Signed-off-by: Stefan Moring <stefanmoring@gmail.com>
Reported-by: Sebastian Reichel <sre@kernel.org>
Fixes: 15a6af9 ("spi: Increase imx51 ecspi burst length based on transfer length")
Tested-by: Sebastian Reichel <sre@kernel.org>
Link: https://lore.kernel.org/r/20230917164037.29284-1-stefanmoring@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-imx.c

@@ -662,7 +662,7 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
 		if (spi_imx->count >= 512)
 			ctrl |= 0xFFF << MX51_ECSPI_CTRL_BL_OFFSET;
 		else
-			ctrl |= (spi_imx->count*8 - 1)
+			ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
 				<< MX51_ECSPI_CTRL_BL_OFFSET;
 	}