ENYO-720: Reassigned the base unit to 12

Revert https://github.com/enyojs/moonstone/pull/1882/files

Issue:
webOS Lite version needs previous base unit of rem for Demo.

Fix:
We temporally revert the fix for Demo.

DCO-1.1-Signed-Off-By: Kunmyon Choi kunmyon.choi@lge.com
Merge pull request #1885 from enyojs/ENYO-720-revert-kunmyonchoi

ENYO-720: Reassigned the base unit to 12