spi/spi-pl022: Use GFP_ATOMIC for allocation from tasklet

tasklets don't allow invocation to sleeping routines. In configure_dma()
routine, sg_alloc_table() was called with GFP_KERNEL flag and so this causes
crash when called from tasklet.

Replace GFP_KERNEL with GFP_ATOMIC to get this fixed.
Signed-off-by: NViresh Kumar <viresh.kumar@st.com>
Tested-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-pl022.c

@@ -1019,11 +1019,11 @@ static int configure_dma(struct pl022 *pl022)
 	pages = (pl022->cur_transfer->len >> PAGE_SHIFT) + 1;
 	dev_dbg(&pl022->adev->dev, "using %d pages for transfer\n", pages);
 
-	ret = sg_alloc_table(&pl022->sgt_rx, pages, GFP_KERNEL);
+	ret = sg_alloc_table(&pl022->sgt_rx, pages, GFP_ATOMIC);
 	if (ret)
 		goto err_alloc_rx_sg;
 
-	ret = sg_alloc_table(&pl022->sgt_tx, pages, GFP_KERNEL);
+	ret = sg_alloc_table(&pl022->sgt_tx, pages, GFP_ATOMIC);
 	if (ret)
 		goto err_alloc_tx_sg;