Fix rounded corners not showing when only top and bottom radius are set.

The changed condition compared the all default, top and bottom to default
one which is wrong.

This cl also fix that the color inversion observor might not re-register
when screendecoration changes in below order:
has screenDecor-> no screenDecor -> has screenDecor.

Bug: 171018853
Test: atest ScreenDecorationsTest.
Change-Id: I52ccc9f4246cdcd0bedf24925dd1e3a24d22fe58