staging: lustre: simplify l_wait_event when intr handler but no timeout.

If l_wait_event() is given a function to be called on a signal,
but no timeout or timeout handler, then the intr function is simply
called at the end if the wait was aborted by a signal.
So a simpler way to write the code (in the one place this case is
used) it to open-code the body of the function after the
wait_event, if -ERESTARTSYS was returned.

Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>