Platform/LeMaker: Fix missing dependency on VariablePolicyHelperLib
The CelloBoard platform firmware build breaks due to the missing
dependency on VariablePolicyHelperLib.
Therefore, to satisfy the dependency include VariablePolicyHelperLib
in the LibraryClasses.common section.
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>