bitbake: depexp: don't use undefined variable 'logging'

This fixes an issue when trying to use depexp without specifying a
recipe. Before change:

  $ bitbake -g -udepexp
  Traceback (most recent call last):
    File ".../bitbake/bin/bitbake", line 382, in <module>
      ret = main()
    File ".../bitbake/bin/bitbake", line 370, in main
      return ui_module.main(server_connection.connection, server_connection.events, configParams)
    File ".../bitbake/lib/bb/ui/depexp.py", line 201, in main
      logger.error(cmdline['msg'])
  NameError: global name 'logger' is not defined

After change:

  $ bitbake -g -udepexp
  Please specify a package name for dependency graph generation.

(Bitbake rev: 984ad90b2f1e29634dc79803a4a0404ab0534039)

Signed-off-by: Olof Johansson <olof.johansson@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/depexp.py

@@ -198,7 +198,7 @@ def main(server, eventHandler, params):
             print("Nothing to do.  Use 'bitbake world' to build everything, or run 'bitbake --help' for usage information.")
             return 1
         if 'msg' in cmdline and cmdline['msg']:
-            logger.error(cmdline['msg'])
+            print(cmdline['msg'])
             return 1
         cmdline = cmdline['action']
         if not cmdline or cmdline[0] != "generateDotGraph":