Don't assume HiiDatabase has been present at the entrypoint and don't assume HiiDatabase and HiiFont are on the same handle according to the UEFI spec.

Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Elvin Li <elvin.li@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14236 6f19259b-4bc3-4df7-8a09-765794883524