fuse: use per req lock for lock/unlock_request()

Reuse req->waitq.lock for protecting FR_ABORTED and FR_LOCKED flags.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

diff --cc fs/fuse/dev.c
Simple merge

diff --cc fs/fuse/fuse_i.h
Simple merge