This was set to true by default prior to U QPR2.
Test: Open settings and notice that dual pane layout is back
Change-Id: Ide44ecbe7e30d6bf26d9c9358e46c71b35c66250
So far, tablets with telephony have been inheriting from
common_full_phone.mk, but that's not really proper because
such makefile now enables one-handed mode support
(setting prop ro.support_one_handed_mode to true).
Fix this by creating new makefiles that can be used also
to include more tablet-specific configs moving forward.
Change-Id: I90c22badb17911ef5e873299d986204718300e6c