MIPS: ralink: add memory definition for RT3883

Populate struct soc_info with the data that describes our RAM window.

Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5182/

arch/mips/include/asm/mach-ralink/rt3883.h

@@ -245,4 +245,8 @@
 #define RT3883_FLASH_CFG_WIDTH_16BIT	0x1
 #define RT3883_FLASH_CFG_WIDTH_32BIT	0x2
 
+#define RT3883_SDRAM_BASE		0x00000000
+#define RT3883_MEM_SIZE_MIN		2
+#define RT3883_MEM_SIZE_MAX		256
+
 #endif /* _RT3883_REGS_H_ */