net: Use bool in netdevice.h helpers.

Specifically use it in napi_disable_pending(), napi_schedule_prep(),
napi_reschedule(), netif_tx_queue_stopped(), netif_queue_stopped(),
netif_xmit_stopped(), netif_xmit_frozen_or_stopped(), netif_running(),
__netif_subqueue_stopped(), netif_subqueue_stopped(),
netif_is_multiquue(), netif_carrier_ok(), netif_dormant(),
netif_oper_up(), netif_device_present(), __netif_tx_trylock(),
net_gso_ok(), skb_gso_ok(), netif_needs_gso(), and
netif_is_bond_slave().

Signed-off-by: David S. Miller <davem@davemloft.net>