[PATCH] relayfs: add relayfs_remove_file()

This patch adds and exports relayfs_remove_file(), for API symmetry (with
relayfs_create_file()).

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>