mmc: sdhci-s3c: fix potential NULL dereference

sc->clk_bus[ptr] could be NULL.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-s3c.c

@@ -567,8 +567,10 @@ static int __devinit sdhci_s3c_probe(struct platform_device *pdev)
 
  err_req_regs:
 	for (ptr = 0; ptr < MAX_BUS_CLK; ptr++) {
-		clk_disable(sc->clk_bus[ptr]);
-		clk_put(sc->clk_bus[ptr]);
+		if (sc->clk_bus[ptr]) {
+			clk_disable(sc->clk_bus[ptr]);
+			clk_put(sc->clk_bus[ptr]);
+		}
 	}
 
  err_no_busclks: