[vmw_log] 'panic' is an 'error' too.

VPXD prints out the stackframes in the log files when it terminates
abnormally. These log messages have a log level of 'panic'. I guess
these qualify as 'error' as well.
Merge pull request #114 from sureshsundriyal/master

[vmw_log] 'panic' is an 'error' too.