Consolidate arch-specific mem_malloc_init() implementations

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index f3bced4..241db8c 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -1520,6 +1520,21 @@
 	return (void *)old;
 }
 
+#ifndef CONFIG_X86
+/*
+ * x86 boards use a slightly different init sequence thus they implement
+ * their own version of mem_malloc_init()
+ */
+void mem_malloc_init(ulong start, ulong size)
+{
+	mem_malloc_start = start;
+	mem_malloc_end = start + size;
+	mem_malloc_brk = start;
+
+	memset((void *)mem_malloc_start, 0, size);
+}
+#endif
+
 /* field-extraction macros */
 
 #define first(b) ((b)->fd)