vfs: spread struct mount - __lookup_mnt() result

switch __lookup_mnt() to returning struct mount *; callers adjusted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/internal.h
Simple merge

diff --cc fs/mount.h
Simple merge

diff --cc fs/namei.c
Simple merge

diff --cc fs/namespace.c
Simple merge

diff --cc fs/pnode.c
Simple merge