virtio-devices: Allowing SYS_write syscall for virtio-net-ctl thread

"debug!" marco is used in virtio-devices/src/epoll_helper.rs. When"-vvv"
and "--log-file" option was specified, the missing "SYS_write" rule
caused a "bad system call" crash.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>

virtio-devices/src/seccomp_filters.rs

@@ -181,6 +181,7 @@ fn virtio_net_ctl_thread_rules() -> Result<Vec<SyscallRuleSet>, Error> {
         allow_syscall(libc::SYS_read),
         allow_syscall(libc::SYS_rt_sigprocmask),
         allow_syscall(libc::SYS_sigaltstack),
+        allow_syscall(libc::SYS_write),
     ])
 }