[PATCH] ARM: 2640/1: Adds DRAM/BANKSIZE_MASK definitions for S3C2400

Patch from Lucas Correia Villa Real

Adds DRAM refresh definitions and sets the BANKSIZE_MASK for the S3C2400 on
include/asm-arm/arch-s3c2400/regs-mem.h

Signed-off-by: Lucas Correia Villa Real
Signed-off-by: Ben Dooks
Signed-off-by: Russell King