spi: dw: Unmask IRQs after enabling the chip

It's theoretically erroneous to enable IRQ before the chip is turned on.
If IRQ handler gets executed before the chip is enabled, then any data
written to the Tx FIFO will be just ignored.

I say "theoretically" because we haven't noticed any problem with that,
but let's fix it anyway just in case...
Signed-off-by: NSerge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201007235511.4935-12-Sergey.Semin@baikalelectronics.ruSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-dw-core.c

@@ -376,8 +376,6 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 			spi_enable_chip(dws, 1);
 			return ret;
 		}
-	} else {
-		dw_spi_irq_setup(dws);
 	}
 
 	spi_enable_chip(dws, 1);
@@ -385,6 +383,8 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 	if (dws->dma_mapped)
 		return dws->dma_ops->dma_transfer(dws, transfer);
 
+	dw_spi_irq_setup(dws);
+
 	return 1;
 }