dlm: use SO_SNDTIMEO_NEW instead of SO_SNDTIMEO_OLD

Eliminate one more use of 'struct timeval' from the kernel so
we can eventually remove the definition as well.

The kernel supports the new format with a 64-bit time_t version
of timeval here, so use that instead of the old timeval.

Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>