1. Updated some files’ description files in MdePkg, EdkModulePkg & EdkNt32Pkg.

2.	Update .msa files to add some missing files files in MdePkg 
3.	Add Help text to Mde Library related PCDs.
4.	Fix some bugs in CpuId.S and CpuIdEx.S.


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@919 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BasePerformanceLibNull/BasePerformanceLibNull.msa

@@ -5,8 +5,9 @@
     <ModuleType>BASE</ModuleType>
     <GuidValue>FC120ED3-40E1-46dc-8C9C-AAE3CA139ACF</GuidValue>
     <Version>1.0</Version>
-    <Abstract>Component description file for the entry point to a EFIDXE Drivers</Abstract>
-    <Description>FIX ME!</Description>
+    <Abstract>Component description file for NULL Performance Library</Abstract>
+    <Description>Performance Library that layers on top of the Base Library to measure start
+      and end times using CPU specific timer services if they are available.</Description>
     <Copyright>Copyright (c) 2006, Intel Corporation.</Copyright>
     <License>All rights reserved. This program and the accompanying materials
       are licensed and made available under the terms and conditions of the BSD License
@@ -46,8 +47,8 @@
     <PcdEntry PcdItemType="FIXED_AT_BUILD">
       <C_Name>PcdPerformanceLibraryPropertyMask</C_Name>
           <TokenSpaceGuidCName>gEfiMdePkgTokenSpaceGuid</TokenSpaceGuidCName>
-
-      <HelpText/>
+      <HelpText>The bitmask of flags that specify the enable/disable of
+                Performance Measurement.</HelpText>
     </PcdEntry>
   </PcdCoded>
 </ModuleSurfaceArea>