Bulk editing power outlets requires specificying an outlet type

[jeremystretch]

Environment

• Python version: 3.6.9
• NetBox version: 2.7.4

Steps to Reproduce

1. Navigate to a device with multiple power outlets
2. Select multiple outlets and click "edit" at the bottom of the list
3. Attempt to change an attribute other than type

Expected Behavior

All of the available fields should be optional.

Observed Behavior

The bulk edit form requires the user to select one of the available outlet types. This field should be available but not required.