Set minimum scaled width/height to 1

Applications could be launched on a secondary display that
has lower density than default display. While some applications
may use 1x1 image resource as activity background, the scaled
width/height would be 0 if down scaling the 1x1 image with
scale ratio that is less than 1/2.

Making sure the scaled width/height won’t less than 1 to
prevent application crashed.

Bug: 117749148
Test: Launch app on secondary display

Change-Id: I73567dd237736466d0bc423485359d50073d86c1