ARM: DRA7: EMIF: Update SDRAM_REF_CTRL register value

The value in SDRAM_REF_CTRL controls the delay time between
the initial rising edge of DDR_RESETn to rising edge of DDR_CKE
(JEDEC specs this as 500us). In order to achieve this, SDRAM_REF_CTRL
should be written with a value corresponding to 500us delay before
starting DDR initialization sequence, and configure proper
value at the end of sequence.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

arch/arm/include/asm/emif.h

@@ -1149,6 +1149,7 @@ struct emif_regs {
 	u32 sdram_config;
 	u32 sdram_config2;
 	u32 ref_ctrl;
+	u32 ref_ctrl_final;
 	u32 sdram_tim1;
 	u32 sdram_tim2;
 	u32 sdram_tim3;