spi: dw: Initialize n_bytes before the memory barrier

Since n_bytes field of the DW SPI private data is also utilized by the
IRQ handler, we need to make sure it' initialization is done before the
memory barrier.
Signed-off-by: NSerge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920112914.26501-4-Sergey.Semin@baikalelectronics.ruSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-dw-core.c

@@ -299,6 +299,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 
 	dws->dma_mapped = 0;
 	spin_lock_irqsave(&dws->buf_lock, flags);
+	dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
 	dws->tx = (void *)transfer->tx_buf;
 	dws->tx_end = dws->tx + transfer->len;
 	dws->rx = transfer->rx_buf;
@@ -323,7 +324,6 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 	}
 
 	transfer->effective_speed_hz = dws->max_freq / chip->clk_div;
-	dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
 
 	cr0 = dws->update_cr0(master, spi, transfer);
 	dw_writel(dws, DW_SPI_CTRLR0, cr0);