ArmVirtPkg: remove status code support

Commit 7b1dc6c5 'ArmVirtPkg: switch to generic ResetSystemRuntimeDxe'
replaced all references in ArmVirtPkg to the deprecated ResetRuntimeDxe
from EmbeddedPkg with the well maintained generic alternative that lives
in MdeModulePkg.

However, as it turns out, the generic driver has a dependency on the
library class ReportStatusCodeLib, whose default resolution is an
implementation that is not safe for use at runtime, resulting in crashes
when trying to invoke it from the OS.

Since we have no use for status codes in any of the ArmVirtPkg
platforms, let's replace all resolutions with a common one to the NULL
implementation.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>