Fix display id for desktop keyboard shotcuts

Currently we were passing the event display id to the SysUI
code that applies the shortcut actions, but the `INVALID_DISPLAY`
value is not supported, so we need to obtain it.

Bug: 318366520
Flag: NA
Test: Flashed on device
Change-Id: I63060e452de26e87060b5439ce5e82ee42a52900