KabylakeOpenBoardPkg: Move EcCommands.h to KabylakeRvp3 board

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2207



EC command details may vary across Kaby Lake boards. This change moves
this set of EC commands to the KabylakeRvp3 directory since these
commands are specifically used by that board at this time.

Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>
Reviewed-by: Jeremy Soller <jeremy@system76.com>