arm: mach-k3: use CFG_MAX_MEM_SIZE

Rather than hard coding the maximum memory size, lets just define the
CFG_MAX_MEM_SIZE so get_effective_memsize() will return the correct
value without modification.

Signed-off-by: Bryan Brattlof <bb@ti.com>
diff --git a/arch/arm/mach-k3/common.h b/arch/arm/mach-k3/common.h
index 2ec60c7..02c7473 100644
--- a/arch/arm/mach-k3/common.h
+++ b/arch/arm/mach-k3/common.h
@@ -10,6 +10,9 @@
 #include <asm/hardware.h>
 #include <mach/security.h>
 
+/* keep ram_top in the 32-bit address space */
+#define CFG_MAX_MEM_MAPPED		0x100000000
+
 #define K3_FIREWALL_BACKGROUND_BIT (8)
 
 struct fwl_data {