Revert "post, memory test: add memory_post_test() to include file"

This reverts commit f18714dd61331b48ab9dc0ef717d61f1441a0e17
which cuases compile errors on a number of boards.

Signed-off-by:  Wolfgang Denk <wd@denx.de>
diff --git a/include/post.h b/include/post.h
index bb3138d..519cef1 100644
--- a/include/post.h
+++ b/include/post.h
@@ -187,7 +187,6 @@
 #define CONFIG_SYS_POST_CODEC		0x00200000
 #define CONFIG_SYS_POST_COPROC		0x00400000
 
-int memory_post_test(int flags);
 #endif /* CONFIG_POST */
 
 #endif /* _POST_H */