ArmVirtPkg/PlatformBootManagerLib: don't launch the Boot Manager Menu

ArmVirtPkg/PlatformBootManagerLib: don't launch the Boot Manager Menu

MdeModulePkg/BDS doesn't launch the UI (Boot Manager Menu) from the
platform side. The platform is expected to store the boot timeout only, in
PcdPlatformBootTimeOut. This is usually done in
PlatformBootManagerBeforeConsole().

(ArmVirtXen is not modified, as it uses PlatformIntelBdsLib from
ArmPlatformPkg, not ArmVirtPkg.)

The patch parallels OvmfPkg commit 8dc0f0a6aab0.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ruiyu Ni <ruiyu.ni@Intel.com>