Fixed the text styling for framework SeekBarPrefenrece

SeekBarPreference provided by framework used the wrong text sizes for
title and summary for both material and non-material layouts. Made the
text appearance consistent with the rest of preference widgets in
framework.
Also note that the framework SeekBarPreference is hidden and cannot
be used externally. The support library version is provided under
v7 preference lib.

Bug: 34068978
Test: Making sure that the text styling matches the rest of framework
preference widgets.

Change-Id: I3947a0bdd995e183e07e73e088916c1a3359ffe0