gve: Remove the code of clearing PBA bit

Clearing the PBA bit from the driver is race prone and it may lead to
dropped interrupt events. This could potentially lead to the traffic
being completely halted.

Fixes: 5e8c5adf ("gve: DQO: Add core netdev features")
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Bailey Forrest <bcf@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>