cxgb4: copy mbox log size to PF0-3 adap instances

copy mbox size to adapter instances of PF0-3 to avoid
mbox log overflow. This fixes the possible protection
fault.

Fixes: baf50868 ("cxgb4: restructure VF mgmt code")
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>