ArmVirtPkg/ArmVirtQemu.dsc: set default for PcdQemuSmbiosValidated

ArmVirtPkg/ArmVirtQemu.dsc: set default for PcdQemuSmbiosValidated

The upcoming OvmfPkg patches will implicitly affect the ArmVirtQemu.dsc
build, necessitating a default value for the new dynamic
PcdQemuSmbiosValidated. Add it.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Wei Huang <wei@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18179 6f19259b-4bc3-4df7-8a09-765794883524