EmbeddedPkg: Add back FfsFindSectionData

In commit c673216f a new input parameter is added in FfsFindSectionData.
That change breaks the build of ArmVirtPkg. In this patch
FfsFindSectionData is added back. It calls FfsFindSectionDataWithHook with
a NULL hook.

Signed-off-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>