octeontx2-pf: Unregister netdev at driver remove

Added unregister_netdev in the driver remove
function. Generally unregister_netdev is called
after disabling all the device interrupts but here
it is called before disabling device mailbox
interrupts. The reason behind this is VF needs
mailbox interrupt to communicate with its PF to
clean up its resources during otx2_stop.
otx2_stop disables packet I/O and queue interrupts
first and by using mailbox interrupt communicates
to PF to free VF resources. Hence this patch
calls unregister_device just before
disabling mailbox interrupts.

Fixes: 3184fb5b

 ("octeontx2-vf: Virtual function driver support")
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>