ArmPkg: Move TimerDxe and ArmArchTimerLib to new ArmGenericTimerCounterLib

ArmPkg: Move TimerDxe and ArmArchTimerLib to new ArmGenericTimerCounterLib

Move TimerDxe and ArmArchTimerLib to ArmGenericTimerCounterLib, and update all
platforms to select the physical counter instance they have been using
implicitly all along.

Contributed-under: TianoCore Contribution Agreement 1.0
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-By: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16078 6f19259b-4bc3-4df7-8a09-765794883524