mMaximumObscuringOpacityForTouch should remain valid

set mMaximumObscuringOpacityForTouch to the defaul value in case
that the system settings contains an invalid value.

Merged-In: I4f15a7573913b503635995d26053bed9aa753a45
Change-Id: I4f15a7573913b503635995d26053bed9aa753a45
Test: presubmit
Bug: 274213741
1 file changed