main: Don't initialize syslog twice for device command

Remove `syslog::init()` in `start_device(), as it's called in
`crosvm_main()`.

BUG=none
TEST=cargo build

Change-Id: Ibe2fe08382525c8eee8dfe33b7949c0f8b0f545e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3165617
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Keiichi Watanabe <keiichiw@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>

src/main.rs

@@ -2558,11 +2558,6 @@ fn start_device(mut args: std::env::Args) -> std::result::Result<(), ()> {
         );
     };
 
-    if let Err(e) = syslog::init() {
-        println!("failed to initialize syslog: {}", e);
-        return Err(());
-    }
-
     if args.len() == 0 {
         print_usage();
         return Err(());