S2IO: Statistics for link up/down and memory allocated/freed

1. Added statistics for link up/down, last link up/down.
2. Statistics for memory allocated/freed.
3. Changed level of some DBG_PRINTs.

Signed-off-by: Sreenivasa Honnur <sreenivasa.honnur@neterion.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>