i40iw: remove unused 'timeval' struct member

There is a stale entry in i40iw_cm_tcp_context that apparently
was copied from the 'nes' driver but never used in i40iw.
I'm trying to kill off all users of timeval as part of the
y2038-safety work, so let's just remove this one.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>