Skip querying for current ticks for filtered out logs. (#2300)

Summary:
Pull Request resolved: #2300

.

Reviewed By: kirklandsign

Differential Revision: D54646899

fbshipit-source-id: f7afac1422d40028ffba11c8c7f34a8e78db5c12

Author: shoumikhin

runtime/platform/log.h

@@ -148,10 +148,10 @@ inline void logf(
  */
 #define ET_LOG(_level, _format, ...)                                          \
   ({                                                                          \
-    et_timestamp_t _timestamp = torch::executor::internal::getLogTimestamp(); \
-    auto _log_level = torch::executor::LogLevel::_level;                      \
+    const auto _log_level = torch::executor::LogLevel::_level;                \
     if (static_cast<uint32_t>(_log_level) >=                                  \
         static_cast<uint32_t>(torch::executor::LogLevel::ET_MIN_LOG_LEVEL)) { \
+      const auto _timestamp = torch::executor::internal::getLogTimestamp();   \
       torch::executor::internal::logf(                                        \
           _log_level,                                                         \
           _timestamp,                                                         \