bnxt_en: implement devlink dev reload fw_activate

Similar to reload driver_reinit, the RTNL lock is held across reload
down and up to prevent interleaving state changes.  But we need to
subsequently release the RTNL lock while waiting for firmware reset
to complete.

Also keep a statistic on fw_activate resets initiated remotely from
other functions.

Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>