Add EDKII_VARIABLE_LOCK_PROTOCOL and the implementation in MdeModulePkg variable drivers.

Add code in BdsDxe driver to call the protocol to mark the read-only variables defined in the UEFI Spec.

Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Guo Dong <guo.dong@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14372 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Include/Guid/SmmVariableCommon.h

@@ -60,6 +60,10 @@ typedef struct {
 // is gEfiSmmVariableProtocolGuid.
 //
 #define SMM_VARIABLE_FUNCTION_GET_STATISTICS          7
+//
+// The payload for this function is SMM_VARIABLE_COMMUNICATE_LOCK_VARIABLE
+//
+#define SMM_VARIABLE_FUNCTION_LOCK_VARIABLE           8
 
 ///
 /// Size of SMM communicate header, without including the payload.
@@ -101,4 +105,6 @@ typedef struct {
   UINT32          Attributes; 
 } SMM_VARIABLE_COMMUNICATE_QUERY_VARIABLE_INFO;
 
+typedef SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME SMM_VARIABLE_COMMUNICATE_LOCK_VARIABLE;
+
 #endif // _SMM_VARIABLE_COMMON_H_