spi: spi-fsl-dspi: fix native data copy

ColdFire is a big-endian cpu with a big-endian dspi hw module,
so, it uses native access, but memcpy breaks the endianness.

So, if i understand properly, by native copy we would mean
be(cpu)->be(dspi) or le(cpu)->le(dspi) accesses, so my fix
shouldn't break anything, but i couldn't test it on LS family,
so every test is really appreciated.

Fixes: 53fadb4d ("spi: spi-fsl-dspi: Simplify bytes_per_word gymnastics")
Signed-off-by: Angelo Dureghello <angelo.dureghello@timesys.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20200529195756.184677-1-angelo.dureghello@timesys.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -250,13 +250,33 @@ struct fsl_dspi {
 
 static void dspi_native_host_to_dev(struct fsl_dspi *dspi, u32 *txdata)
 {
-	memcpy(txdata, dspi->tx, dspi->oper_word_size);
+	switch (dspi->oper_word_size) {
+	case 1:
+		*txdata = *(u8 *)dspi->tx;
+		break;
+	case 2:
+		*txdata = *(u16 *)dspi->tx;
+		break;
+	case 4:
+		*txdata = *(u32 *)dspi->tx;
+		break;
+	}
 	dspi->tx += dspi->oper_word_size;
 }
 
 static void dspi_native_dev_to_host(struct fsl_dspi *dspi, u32 rxdata)
 {
-	memcpy(dspi->rx, &rxdata, dspi->oper_word_size);
+	switch (dspi->oper_word_size) {
+	case 1:
+		*(u8 *)dspi->rx = rxdata;
+		break;
+	case 2:
+		*(u16 *)dspi->rx = rxdata;
+		break;
+	case 4:
+		*(u32 *)dspi->rx = rxdata;
+		break;
+	}
 	dspi->rx += dspi->oper_word_size;
 }