UefiCpuPkg/RegisterCpuFeaturesLib: Add "Test Then Write" Macros.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2040

Add below new micros which test the current value before write the new
value. Only write new value when current value not same as new value.
  CPU_REGISTER_TABLE_TEST_THEN_WRITE32
  CPU_REGISTER_TABLE_TEST_THEN_WRITE64
  CPU_REGISTER_TABLE_TEST_THEN_WRITE_FIELD

Also add below API:
  CpuRegisterTableTestThenWrite

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Cc: Star Zeng <star.zeng@intel.com>

UefiCpuPkg/Include/AcpiCpuData.h

@@ -78,7 +78,8 @@ typedef struct {
   UINT32         Index;                 // offset 4 - 7
   UINT8          ValidBitStart;         // offset 8
   UINT8          ValidBitLength;        // offset 9
-  UINT16         Reserved;              // offset 10 - 11
+  BOOLEAN        TestThenWrite;         // offset 10
+  UINT8          Reserved1;             // offset 11
   UINT32         HighIndex;             // offset 12-15, only valid for MemoryMapped
   UINT64         Value;                 // offset 16-23
 } CPU_REGISTER_TABLE_ENTRY;