fix Undefined Index and Divison by zero

[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined index: cmd in /var/www/hoanoho/homie/report_display.php on line 111, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined index: cmd in /var/www/hoanoho/homie/report_display.php on line 124, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined index: cmd in /var/www/hoanoho/homie/report_display.php on line 138, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: data_ in /var/www/hoanoho/homie/report_display.php on line 291, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: valueset_data in /var/www/hoanoho/homie/report_display.php on line 343, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: valueset_labels in /var/www/hoanoho/homie/report_display.php on line 353, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Warning:  Division by zero in /var/www/hoanoho/homie/report_display.php on line 86, referer: https://192.168.6.135/homie/reports.php
[Tue Oct 14 01:57:52 2014] [error] [client 127.0.0.1] PHP Warning:  Division by zero in /var/www/hoanoho/homie/report_display.php on line 86, referer: https://192.168.6.135/homie/reports.php