tests/checkasm: Remove check on linux perf fd in uninit

The check should be >= 0, not > 0. The check itself is redundant
since uninit only being called after init is success.

Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>

tests/checkasm/checkasm.c

@@ -823,8 +823,7 @@ static int bench_init(void)
 static void bench_uninit(void)
 {
 #if CONFIG_LINUX_PERF
-    if (state.sysfd > 0)
-        close(state.sysfd);
+    close(state.sysfd);
 #endif
 }