persist the changed position values in updateWallpaperOffsetLocked, even with a null mWallpaperTarget

Change-Id: I175773f6e0b3f91c1d983857028a89b959e4e9f2
Automatic translation import

Change-Id: I0b81b54da81b39d2158eeb70123b96a252f14156
Merge branch 'cm/cm-11.0'