IB/ipath: Make ipath_portdata work with struct pid * not pid_t

The official reason is "with the presence of pid namespaces in the
kernel using pid_t-s inside one is no longer safe."

But the reason I fix this right now is the following:

About a month ago (when 2.6.25 was not yet released) there still was a
one last caller of a to-be-deprecated-soon function find_pid() - the
kill_proc() function, which in turn was only used by nfs callback
code.

During the last merge window, this last caller was finally eliminated
by some NFS patch(es) and I was about to finally kill this kill_proc()
and find_pid(), but found, that I was late and the kill_proc is now
called from the ipath driver since commit 58411d1c ("IB/ipath: Head of
Line blocking vs forward progress of user apps").

So here's a patch that fixes this code to use struct pid * and (!)
the kill_pid routine.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ipath/ipath_kernel.h

@@ -159,8 +159,8 @@ struct ipath_portdata {
 	/* saved total number of polled urgent packets for poll edge trigger */
 	u32 port_urgent_poll;
 	/* pid of process using this port */
-	pid_t port_pid;
-	pid_t port_subpid[INFINIPATH_MAX_SUBPORT];
+	struct pid *port_pid;
+	struct pid *port_subpid[INFINIPATH_MAX_SUBPORT];
 	/* same size as task_struct .comm[] */
 	char port_comm[16];
 	/* pkeys set by this use of this port */