Mms: fix quick message layout on 320dp

match_parent no longer works properly on 4.4 for some reason, so
we hardcode it to 300dp.

Also cleaned up how 360dp devices are handled to avoid duplicating
layout.

Before: http://imgur.com/UKo4aUL
After: http://imgur.com/Eu6WMnm

Change-Id: Ic5cd5acaeeaaf56f0033a10924d7f207a2fff175