virtio-net: free xsk_buffs on error in virtnet_xsk_pool_enable()

In the Linux kernel, the following vulnerability has been resolved: virtio-net: free xsk_buffs on error in virtnet_xsk_pool_enable() The selftests added to our CI by Bui Quang Minh recently reveals that there is a mem leak on the error path of virtnet_xsk_pool_enable(): unreferenced object 0xffff88800a68a000 (size 2048): comm "xdp_helper", pid 318, jiffies 4294692778 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 0): __kvmalloc_node_noprof+0x402/0x570 virtnet_xsk_pool_enable+0x293/0x6a0 (drivers/net/virtio_net.c:5882) xp_assign_dev+0x369/0x670 (net/xdp/xsk_buff_pool.c:226) xsk_bind+0x6a5/0x1ae0 __sys_bind+0x15e/0x230 __x64_sys_bind+0x72/0xb0 do_syscall_64+0xc1/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f