ArmPlatformPkg/ArmJunoDxe: don't register OnEndOfDxe event on rev R0

ArmPlatformPkg/ArmJunoDxe: don't register OnEndOfDxe event on rev R0

The ArmJunoDxe driver code registers a callback for the EndOfDxe event,
at which time it does some manipulation of the PCI peripherals on the
board. Given that R0 has no working PCIe, instead of conditionally
performing these operations, omit the registration of the
callback altogether on that platform.

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>