spi: spi-imx: spi_imx_buf_rx_swap_u32(): replace open coded swahw32s()

This patch replaces an open coded swahw32s().

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220502175457.1977983-6-mkl@pengutronix.de


Signed-off-by: Mark Brown <broonie@kernel.org>