IB/mthca: Change command token on timeout

The FW command token is currently only updated on a command completion
event. This means that on command timeout, the same token will be
reused for new command, which results in a mess if the timed out
command *does* eventually complete.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>