spi: spi-fsl-qspi: Reduce devm_ioremap size to 4 times AHB buffer size

Reduce devm_ioremap size to (4 * AHB_BUFER_SIZE) rather than mapping
complete QSPI-Memmory as driver is now independent of flash size.
Flash of any size can be accessed.

Issue was reported on platform where devm_ioremap failure is observed
with size > 256M.
Error log on LS1021ATWR :
 fsl-quadspi 1550000.spi: ioremap failed for resource [mem 0x40000000-0x7fffffff]
 fsl-quadspi 1550000.spi: Freescale QuadSPI probe failed
 fsl-quadspi: probe of 1550000.spi failed with error -12

This change was also suggested previously:
https://patchwork.kernel.org/patch/10508753/#22166385Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Kuldeep Singh <kuldeep.singh@nxp.com>
Signed-off-by: Ashish Kumar <Ashish.kumar@nxp.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Link: https://lore.kernel.org/r/1587037399-18672-1-git-send-email-Ashish.Kumar@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-qspi.c

@@ -876,14 +876,15 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 					"QuadSPI-memory");
-	q->ahb_addr = devm_ioremap_resource(dev, res);
+	q->memmap_phy = res->start;
+	/* Since there are 4 cs, map size required is 4 times ahb_buf_size */
+	q->ahb_addr = devm_ioremap(dev, q->memmap_phy,
+				   (q->devtype_data->ahb_buf_size * 4));
 	if (IS_ERR(q->ahb_addr)) {
 		ret = PTR_ERR(q->ahb_addr);
 		goto err_put_ctrl;
 	}
 
-	q->memmap_phy = res->start;
-
 	/* find the clocks */
 	q->clk_en = devm_clk_get(dev, "qspi_en");
 	if (IS_ERR(q->clk_en)) {