We have converted all makefiles needed to build $(LIBS).
Until this commit we used to grep switch so that U-Boot style
and Kbuild style makefiles coexist.
But we do not need any more.
Goint forward, use always Kbuild style Makefile when adding
a new Makefile
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>