spi: spi-mtk-nor: Don't leak SPI master in probe error path

If the call to devm_spi_register_controller() fails on probe of the
MediaTek SPI NOR driver, the spi_controller struct is erroneously not
freed.

Since commit a1daaa99 ("spi: spi-mtk-nor: use dma_alloc_coherent()
for bounce buffer"), the same happens if the call to
dmam_alloc_coherent() fails.

Since commit 3bfd9103 ("spi: spi-mtk-nor: Add power management
support"), the same happens if the call to mtk_nor_enable_clk() fails.

Fix by switching over to the new devm_spi_alloc_master() helper.

Fixes: 881d1ee9 ("spi: add support for mediatek spi-nor controller")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ikjoon Jang <ikjn@chromium.org>
Cc: <stable@vger.kernel.org> # v5.7+: 5e844cc3: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v5.7+
Cc: Chuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/d5b9f0289465394e73dedb8ec51e180a8f1dffc9.1607286887.git.lukas@wunner.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mtk-nor.c

@@ -781,7 +781,7 @@ static int mtk_nor_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	ctlr = spi_alloc_master(&pdev->dev, sizeof(*sp));
+	ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(*sp));
 	if (!ctlr) {
 		dev_err(&pdev->dev, "failed to allocate spi controller\n");
 		return -ENOMEM;