Skip falsing for desktop devices

Falsing should never be applied on laptops and other desktop
devices.

Bug: 435151039
Flag: EXEMPT desktop only, protected by config
Test: bouncer falsing on cf desktop using tap and mouse clicks
Test: atest FalsingDataProviderTest, atest BrightLineFalsingManagerTest, atest ClassifierTest
Change-Id: I9cd1d830689d26983be2c8b3057ad0a61a902089