ipmi:kcs: Reduce the number of retries

ipmi:kcs: Reduce the number of retries

The retry count was initially set to 10, which with the 5 second
timeouts give 55 seconds to fail a message.

The IPMI spec specifies the 5 second timeout, and it specifies retries
for KCS but does not specify a number.  55 seconds is a long time, so
reduce retries to 2.  It matches the default in the BT state machine.
This is 15 seconds, then, which is still a long time, but more
reasonable.

Signed-off-by: Corey Minyard <corey@minyard.net>