[sonic_py_common] Fix exception in daemon_base.py (sonic-net#5472)

There is a syntax error (self is missing for log_info and log_warning) in signal_handler in daemon_base.py, which causes an exception

Author: bingwang-ms

src/sonic-py-common/sonic_py_common/daemon_base.py

@@ -44,15 +44,15 @@ def __init__(self, log_identifier):
     # Default signal handler; can be overridden by subclass
     def signal_handler(self, sig, frame):
         if sig == signal.SIGHUP:
-            log_info("DaemonBase: Caught SIGHUP - ignoring...")
+            self.log_info("DaemonBase: Caught SIGHUP - ignoring...")
         elif sig == signal.SIGINT:
-            log_info("DaemonBase: Caught SIGINT - exiting...")
+            self.log_info("DaemonBase: Caught SIGINT - exiting...")
             sys.exit(128 + sig)
         elif sig == signal.SIGTERM:
-            log_info("DaemonBase: Caught SIGTERM - exiting...")
+            self.log_info("DaemonBase: Caught SIGTERM - exiting...")
             sys.exit(128 + sig)
         else:
-            log_warning("DaemonBase: Caught unhandled signal '{}'".format(sig))
+            self.log_warning("DaemonBase: Caught unhandled signal '{}'".format(sig))
 
     # Loads platform specific platform module from source
     def load_platform_util(self, module_name, class_name):