Standardize mem_malloc_init() implementation

This lays the groundwork to allow architectures to share a common
mem_malloc_init().

Note that the x86 implementation was not modified as it did not fit the
mold of all other architectures.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/lib_arm/board.c b/lib_arm/board.c
index 62b7874..904ea89 100644
--- a/lib_arm/board.c
+++ b/lib_arm/board.c
@@ -83,14 +83,13 @@
 #endif
 
 static
-void mem_malloc_init (ulong dest_addr)
+void mem_malloc_init (ulong start, ulong size)
 {
-	mem_malloc_start = dest_addr;
-	mem_malloc_end = dest_addr + CONFIG_SYS_MALLOC_LEN;
-	mem_malloc_brk = mem_malloc_start;
+	mem_malloc_start = start;
+	mem_malloc_end = start + size;
+	mem_malloc_brk = start;
 
-	memset ((void *) mem_malloc_start, 0,
-			mem_malloc_end - mem_malloc_start);
+	memset ((void *)mem_malloc_start, 0, size);
 }
 
 
@@ -300,7 +299,8 @@
 	}
 
 	/* armboot_start is defined in the board-specific linker script */
-	mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN);
+	mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN,
+			CONFIG_SYS_MALLOC_LEN);
 
 #ifndef CONFIG_SYS_NO_FLASH
 	/* configure available FLASH banks */