ArmPlatformPkg/ArmJunoDxe: use the generic non-discoverable device support

ArmPlatformPkg/ArmJunoDxe: use the generic non-discoverable device support

Replace the open coded reimplementation of 'PCI emulation' with a pair
of calls into NonDiscoverableDeviceRegistrationLib to register the OHCI
and EHCI controllers. These will be picked up by the generic driver instead.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>