Explore by touch enabled when screen magnification is on.

1. A recently added check was preventing touch exploration being
   disabled when the last touch exploring service was turned off.
   As a consequence enabling explore by touch was initializing the
   input filter with the magnification and the not disabled
   screen magnification features.
bug:7256223

Change-Id: I9ed5457705d625805462e4d316b2c8a5af9aabca