ipmi: fix ipmi_si modprobe hang

Instead of queuing IPMB messages before channel initialization, just
throw them away.  Nobody will be listening for them at this point,
anyway, and they will clog up the queue and nothing will be delivered
if we queue them.

Also set the current channel to the number of channels, as this value
is used to tell if the channel information has been initialized.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Ferenc Wagner <wferi@niif.hu>
Cc: Dan Frazier <dannf@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>