fs: move some file system to fs/Makefile

This commit moves some subdirectories of fs
from the toplevel Makefile to fs/Makefile
using Kbuild descending feature.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 59c7cfd..f4bde33 100644
--- a/Makefile
+++ b/Makefile
@@ -248,17 +248,7 @@
 LIBS-$(CONFIG_OF_EMBED) += dts/libdts.o
 LIBS-y += arch/$(ARCH)/lib/lib$(ARCH).o
 LIBS-y += fs/libfs.o \
-	fs/cbfs/libcbfs.o \
-	fs/cramfs/libcramfs.o \
-	fs/ext4/libext4fs.o \
-	fs/fat/libfat.o \
-	fs/fdos/libfdos.o \
-	fs/jffs2/libjffs2.o \
-	fs/reiserfs/libreiserfs.o \
-	fs/sandbox/libsandboxfs.o \
-	fs/ubifs/libubifs.o \
-	fs/yaffs2/libyaffs2.o \
-	fs/zfs/libzfs.o
+	fs/fat/libfat.o
 LIBS-y += net/libnet.o
 LIBS-y += disk/libdisk.o
 LIBS-y += drivers/libdrivers.o