ipmi: Fix SSIF flag requests

Commit 89986496

 ("ipmi: Turn off all activity on an idle ipmi
interface") modified the IPMI code to only request events when the
driver had somethine waiting for events.  The SSIF code, however,
was using the event fetch request to also fetch the flags.

Add a timer and the proper handling for the upper layer telling
whether flags fetches are required.

Reported-by: Kamlakant Patel <Kamlakant.Patel@cavium.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Tested-by: Kamlakant Patel <kamlakant.patel@cavium.com>