Marvell: Add VariableFlashInfoLib

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3479



This patch adds an instance for the library class VariableFlashInfoLib
that was recently introduced in MdeModulePkg. This change is made to
allow the new variable driver to build that has a dependency on
this library class and does not require any further platform changes.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Sunny Wang <sunny.wang@arm.com>