Split out textColor to its own separate value.

If a theme modifies the dialer text to white and still leaves
the call log white, the text would be white-on-white. This change
allows the call_log_list_item_extra text to be changed separately.

Change-Id: I18f10494dd6987e6dee5655b5662b94622ca874f
(cherry picked from commit 176b6ab6)