Remove unnecessary `require 'scss_lint'` lines

These lines were unnecessary since the `scss_lint` module has already
been loaded by the time these files are executed.

Change-Id: I708316bf25e560c532295980cd9d77e88a683459
Reviewed-on: https://gerrit.causes.com/27807
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>