datapath: compat: remove __net_init and __net_exit annotations.

datapath: compat: remove __net_init and __net_exit annotations.

net_namespace-device can get registered after module init, e.g. vxlan
registers name-space-device on port add.  On kernel without namespace
support __net_init is defined as __init which cause panic on vxlan port
add. Following patch fixes it.

BUG: unable to handle kernel paging request at ffffffffa02b6293
IP: [<ffffffffa02b6293>] 0xffffffffa02b6293
PGD 1a87067 PUD 1a8b063 PMD 8371de067 PTE 0
Oops: 0010 [#1] SMP
Process ovs-vswitchd (pid: 10330, threadinfo ffff8808367fe000, task
		      f880839e16aa0)
Stack:
Call Trace:
 [<ffffffff8144b254>] ? register_pernet_gen_device+0x74/0xd0
 [<ffffffffa027e220>] ? vxlan_rcv+0x0/0x60 [openvswitch]
 [<ffffffffa0280a7b>] vxlan_handler_add+0x3cb/0x480 [openvswitch]
 [<ffffffffa027e1f4>] vxlan_tnl_create+0xc4/0xf0 [openvswitch]
 [<ffffffffa027b6f3>] ovs_vport_add+0x53/0xb0 [openvswitch]
 [<ffffffffa0273bc6>] new_vport+0x16/0x60 [openvswitch]
 [<ffffffffa0276399>] ovs_vport_cmd_new+0x109/0x210 [openvswitch]
 [<ffffffff81478f80>] genl_rcv_msg+0x1d0/0x210
 [<ffffffff81477e29>] netlink_rcv_skb+0xa9/0xd0
 [<ffffffff81478d95>] genl_rcv+0x25/0x40
 [<ffffffff81477a63>] netlink_unicast+0x283/0x2d0
 [<ffffffff814783de>] netlink_sendmsg+0x1fe/0x2e0
 [<ffffffff8143c8d3>] sock_sendmsg+0x123/0x150
 [<ffffffff8143e0b6>] __sys_sendmsg+0x406/0x420
 [<ffffffff8143e2d9>] sys_sendmsg+0x49/0x90
 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
Code:  Bad RIP value.
RIP  [<ffffffffa02b6293>] 0xffffffffa02b6293

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Bug #19178