openvswitch: fix memory leak at failed datapath creation

In the Linux kernel, the following vulnerability has been resolved:

openvswitch: fix memory leak at failed datapath creation

ovs_dp_cmd_new()->ovs_dp_change()->ovs_dp_set_upcall_portids()

allocates array via kmalloc.

If for some reason new_vport() fails during ovs_dp_cmd_new()

dp->upcall_portids must be freed.

Add missing kfree.

Kmemleak example:

unreferenced object 0xffff88800c382500 (size 64):

comm "dump_state", pid 323, jiffies 4294955418 (age 104.347s)

hex dump (first 32 bytes):

5e c2 79 e4 1f 7a 38 c7 09 21 38 0c 80 88 ff ff ^.y..z8..!8.....

03 00 00 00 0a 00 00 00 14 00 00 00 28 00 00 00 ............(...

backtrace:

[<0000000071bebc9f>] ovs_dp_set_upcall_portids+0x38/0xa0

[<000000000187d8bd>] ovs_dp_change+0x63/0xe0

[<000000002397e446>] ovs_dp_cmd_new+0x1f0/0x380

[<00000000aa06f36e>] genl_family_rcv_msg_doit+0xea/0x150

[<000000008f583bc4>] genl_rcv_msg+0xdc/0x1e0

[<00000000fa10e377>] netlink_rcv_skb+0x50/0x100

[<000000004959cece>] genl_rcv+0x24/0x40

[<000000004699ac7f>] netlink_unicast+0x23e/0x360

[<00000000c153573e>] netlink_sendmsg+0x24e/0x4b0

[<000000006f4aa380>] sock_sendmsg+0x62/0x70

[<00000000d0068654>] ____sys_sendmsg+0x230/0x270

[<0000000012dacf7d>] ___sys_sendmsg+0x88/0xd0

[<0000000011776020>] __sys_sendmsg+0x59/0xa0

[<000000002e8f2dc1>] do_syscall_64+0x3b/0x90

[<000000003243e7cb>] entry_SYSCALL_64_after_hwframe+0x63/0xcd