Fixed references to removed mobile theme in theme footers. refs #1708

This PR removes references to the mobile theme in two theme footers.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| Refs tickets  | #1708
| License       | MIT
| Doc PR        |