free_pidmap: turn it into free_pidmap(struct upid *)

The callers of free_pidmap() pass 2 members of "struct upid", we can just
pass "struct upid *" instead.  Shaves off 10 bytes from pid.o.

Also, simplify the alloc_pid's "out_free:" error path a little bit.  This
way it looks more clear which subset of pid->numbers[] we are freeing.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc :Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>