OMAP2/3: GPMC: ensure valid clock pointer

Ensure valid clock pointer during GPMC init.  Fixes compiler
warning about potential use of uninitialized variable.
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/gpmc.c

@@ -505,7 +505,7 @@ static void __init gpmc_mem_init(void)
 void __init gpmc_init(void)
 {
 	u32 l;
-	char *ck;
+	char *ck = NULL;
 
 	if (cpu_is_omap24xx()) {
 		ck = "core_l3_ck";
@@ -521,6 +521,9 @@ void __init gpmc_init(void)
 		l = OMAP44XX_GPMC_BASE;
 	}
 
+	if (WARN_ON(!ck))
+		return;
+
 	gpmc_l3_clk = clk_get(NULL, ck);
 	if (IS_ERR(gpmc_l3_clk)) {
 		printk(KERN_ERR "Could not get GPMC clock %s\n", ck);