UefiPayloadPkg: Include UniversalPayLoad modules in UefiPayloadPkg.dsc

Add a new macro "UNIVERSAL_PAYLOAD" to build Universal Payload.

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

UefiPayloadPkg/UefiPayloadPkg.fdf

@@ -52,8 +52,9 @@ READ_STATUS        = TRUE
 READ_LOCK_CAP      = TRUE
 READ_LOCK_STATUS   = TRUE
 
+!if $(UNIVERSAL_PAYLOAD) == FALSE
 INF UefiPayloadPkg/UefiPayloadEntry/UefiPayloadEntry.inf
-
+!endif
 FILE FV_IMAGE = 4E35FD93-9C72-4c15-8C4B-E77F1DB2D793 {
     SECTION FV_IMAGE = DXEFV
 }