autofs: update fs/autofs4/Makefile

Update Makefile to build from source in fs/autofs instead of fs/autofs4.

Link: http://lkml.kernel.org/r/152626706824.28589.1915028175544560855.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/autofs4/Makefile

@@ -4,4 +4,6 @@
 
 obj-$(CONFIG_AUTOFS4_FS) += autofs4.o
 
-autofs4-objs := init.o inode.o root.o symlink.o waitq.o expire.o dev-ioctl.o
+autofs4-objs := ../autofs/init.o ../autofs/inode.o ../autofs/root.o \
+	../autofs/symlink.o ../autofs/waitq.o ../autofs/expire.o \
+	../autofs/dev-ioctl.o