Check input device's all sub devices for isEnabled()

We now allow individual sub devices in an input device to be enabled
and disabled, the isEnalbed() function should check all sub devices and return
true if any device is enabled.

Bug: 161634265
Bug: 175953789
Test: atest inputflinger_tests
Change-Id: Ia5b93089f34d464e9c61595af621e3711837171b