Silicon/Hisilicon: add VariablePolicy resolutions

Add resolutions for
- VariablePolicyLib
- VariablePolicyHelperLib
- VariablePolicyLib (DXE_RUNTIME_DRIVER)
to Hisilicon platforms.

Cc: Ming Huang <huangming23@huawei.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Leif Lindholm <leif@nuviainc.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>