ArmVirtPkg/PlatformBootManagerLib: add missing report status code call

ArmVirtPkg/PlatformBootManagerLib: add missing report status code call

Consumers of status code reports may rely on a status code to be
reported when the ReadyToBoot event is signalled. For instance,
FirmwarePerformanceDxe will fail to install the FPDT ACPI table
in this case. So add the missing call.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>