Move initf_malloc() to a common place

To allow this function to be used from SPL, move it to the malloc()
code.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index b2ce063..b5bb051 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -3261,6 +3261,17 @@
   }
 }
 
+int initf_malloc(void)
+{
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	assert(gd->malloc_base);	/* Set up by crt0.S */
+	gd->malloc_limit = CONFIG_SYS_MALLOC_F_LEN;
+	gd->malloc_ptr = 0;
+#endif
+
+	return 0;
+}
+
 /*
 
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