Best fit the external display

Best fit the external display

NO_REF_TASK
tested:
1) set persist.remixos.disp_best_fit to true
2) plugin the HDMI, the resolution should be the one fit the primary
   screen (i.e. the resolution should be larger than or equal to primery
   resolution, and it is the closest one)

3) set persist.remixos.disp_best_fit to false
4) plugin HDMI again, the external display will use the default
   resolution.

Change-Id: I80b0fe6e7cc676ce1915f07f267204734bfc645f