sfc: populate the timer reload field

The timer mode register now has a separate field for the reload value.
Since we always use this timer with the reload (for interrupt moderation)
we set this to the same as the initial value.

Previous hardware ignores this field, so we can safely set these bits
on all hardware that uses this register.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>