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 <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

arch/arm/mach-omap2/gpmc.c

···
 void __init gpmc_init(void)
 {
 	u32 l;
-	char *ck;
+	char *ck = NULL;
 
 	if (cpu_is_omap24xx()) {
 		ck = "core_l3_ck";
···
 		ck = "gpmc_ck";
 		l = OMAP44XX_GPMC_BASE;
 	}
+
+	if (WARN_ON(!ck))
+		return;
 
 	gpmc_l3_clk = clk_get(NULL, ck);
 	if (IS_ERR(gpmc_l3_clk)) {