Respect add focusables flags

This CL fixes 2 bugs in View's addFocusables implementations.

1) addFocusables(list, dir) method was always returning focusables in
touch mode even if the device is not in touch mode.

2) addFocusables(list, dir, mode) was not respecting the provided mod.

Bug: 28745577
Change-Id: I9b9e5af27f8f5b1bb3cc601584fdad7c73e54a5d