IB/ehca: Remove tgid checking

Pavel Emelyanov <xemul@openvz.org> mentioned in <http://lkml.org/lkml/2008/3/17/131>
that the task_struct->tgid field is about to become deprecated, so the
uses in the ehca driver need to be fixed up.

However, all the uses in ehca are for some object ownership checking
that is not really needed, and anyway is implementing a policy that
should be in common code rather than a low-level driver.  So just
remove all the checks.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>