UefiPayloadPkg: Use SECURITY_STUB_ENABLE to control the SecurityStubDxe

UefiPayloadPkg: Use SECURITY_STUB_ENABLE to control the SecurityStubDxe

The SecurityStubDxe driver may be provided by platform payload.
In UefiPayloadPkg\UefiPayloadPkg.fdf file, SecurityStubDxe should only
be included if SECURITY_STUB_ENABLE is TRUE

Cc: Guo Dong <guo.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>