tunneling: Don't shadow vport when generating cache.

tunneling: Don't shadow vport when generating cache.

When generating the tunnel header cache we have two vports that we
are working with: the sender and destination.  Unfortunately, both of
these use the name 'vport'.  This renames the destination to avoid
shadowing the sender.  This doesn't actually fix a bug because the
compiler correctly uses the right one, even when shadowed.

Found with sparse.

Reported-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>