net/ena: fix potential access to freed memory during device reset

If the ena driver detects that the device is not behave as expected,
it tries to reset the device.
The reset flow calls ena_down, which will frees all the resources
the driver allocates and then it will reset the device.

This flow can cause memory corruption if the device is still writes
to the driver's memory space.
To overcome this potential race, move the reset before the device
resources are freed.

Signed-off-by: Netanel Belgazal <netanel@annapurnalabs.com>
Signed-off-by: David S. Miller <davem@davemloft.net>