MdeModulePkg/SetupBrowserDxe: Fix IsZeroGuid() ASSERT.
    
    From the function description of GetIfrBinaryData(), FormSetGuid can be
    NULL. However, FormSetGuid is passed to IsZeroGuid(). This causes exception
    when FormSetGuid is NULL.
    
    Signed-off-by: Nickle Wang <nickle.wang@hpe.com>
    Reviewed-by: Dandan Bi <dandan.bi@intel.com>