Fix some Holo text color bugs

Fix Switch text color in Holo Light to contrast better - always light
text against the dark switch thumb.

Fix a bug where TextAppearance.Holo.Small.Inverse was using
?textColorPrimaryInverse instead of ?textColorSecondaryInverse.
("Small" TextAppearance always uses the secondary color.)

Bug 6967184

Change-Id: I039bf089d4c7aa257ec4f600df6c0d2066164194