bnx2x: free the mac filter group list before freeing the cmd

The group list must be freed prior to freeing the command otherwise
we have a use-after-free.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: Yuval Mintz <Yuval.Mintz@qlogic.com>
Cc: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>