be2net: avoid napi_disable() when it has not been enabled

When RQ creation fails in be_open(), driver jumps to be_close() where
napi_disable() is done without a prior napi_enable(); leading to a hang.
This change is needed as there is no way to see if napi is enable/disabled.

Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>