TI OMAP3: make gpmc_config as const

gpmc_config should not be a variant as it is board specific
hence make it a const parameter

Fixes issues identified by Dirk:
- build issue for zoom2
- warnings for all other OMAP3 platforms using nand/onenand etc

Signed-off-by: Nishanth Menon <nm@ti.com>

include/asm-arm/arch-omap3/sys_proto.h

@@ -34,7 +34,7 @@ void memif_init(void);
 void sdrc_init(void);
 void do_sdrc_init(u32, u32);
 void gpmc_init(void);
-void enable_gpmc_cs_config(u32 *gpmc_config, struct gpmc_cs *cs, u32 base,
+void enable_gpmc_cs_config(const u32 *gpmc_config, struct gpmc_cs *cs, u32 base,
 			u32 size);
 
 void watchdog_init(void);