Makefile: rename all libraries to built-in.o

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/board/esteem192e/u-boot.lds b/board/esteem192e/u-boot.lds
index 87642d6..59a86bf 100644
--- a/board/esteem192e/u-boot.lds
+++ b/board/esteem192e/u-boot.lds
@@ -18,8 +18,8 @@
 
     arch/powerpc/cpu/mpc8xx/start.o	(.text*)
     arch/powerpc/cpu/mpc8xx/traps.o	(.text*)
-    net/libnet.o			(.text*)
-    board/esteem192e/libesteem192e.o	(.text*)
+    net/built-in.o			(.text*)
+    board/esteem192e/built-in.o		(.text*)
 
     . = env_offset;
     common/env_embedded.o		(.text*)