[PATCH] afs: add lock annotations to afs_proc_cell_servers_{start,stop}

afs_proc_cell_servers_start acquires a lock, and afs_proc_cell_servers_stop
releases that lock.  Add lock annotations to these two functions so that
sparse can check callers for lock pairing, and so that sparse will not
complain about these functions since they intentionally use locks in this
manner.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>