Refine question value update logic.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>


git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg@14673 6f19259b-4bc3-4df7-8a09-765794883524
Export one interface to support 3rd party to change question attribute, such as hide/gray out.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>



git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg@14678 6f19259b-4bc3-4df7-8a09-765794883524