IntelSiliconPkg: Fix VS2015 NOOPT IA32 build failure in IntelVTdDxe

IntelSiliconPkg: Fix VS2015 NOOPT IA32 build failure in IntelVTdDxe

There are VS2015 NOOPT IA32 build failure like below in IntelVTdDxe.
XXX.lib(XXX.obj) : error LNK2001: unresolved external symbol __allshl
XXX.lib(XXX.obj) : error LNK2001: unresolved external symbol __aullshr

This patch is to update Vtd.h to use UINT32 instead of UINT64 for
bitfields in structure definition, and also update IntelVTdDxe code
accordingly.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>