PhotoPhase: Remove references to inexistent strings

These were removed in 22aecd384c4ec60c8c663540875beede462d40b7
but not removed from the preferences xml.

Build was not broken until today's translation sync because
it picked the missing strings from the translations.

Change-Id: Ia4db2c4ef4a3dcbc6b9be0c9d1f22ab2b4423b50