Vlv2TbltDevicePkg: Add /m flag for multi-processor build

https://bugzilla.tianocore.org/show_bug.cgi?id=274

Add support for multi-processor builds using a /m flag.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: David Wei <david.wei@intel.com>
Cc: Mang Guo <mang.guo@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

Vlv2TbltDevicePkg/Build_IFWI.bat

@@ -45,6 +45,11 @@ if /i "%~1"=="/y" (
     shift
     goto OptLoop
 )
+if /i "%~1"=="/m" (
+    set Build_Flags=%Build_Flags% /m
+    shift
+    goto OptLoop
+)
 if /i "%~1" == "/c" (
     set Build_Flags=%Build_Flags% /c
     shift