qede: Fix ref-cnt usage count

Rebooting while qedr is loaded with a VLAN interface present
results in unregister_netdevice waiting for the usage count
to become free.
The fix is that rdma devices should be removed before unregistering
the netdevice, to assure all references to ndev are decreased.

Fixes: cee9fbd8 ("qede: Add qedr framework")
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: Michal Kalderon <michal.kalderon@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>