x86, cpu: Add cpufeature flag for PCIDs

This patch add a flag for Process-Context Identifiers (PCIDs) aka
Address Space Identifiers (ASIDs) aka Tagged TLB support.

Signed-off-by: Arun Thomas <arun.thomas@gmail.com>
Link: http://lkml.kernel.org/r/1313782943-3898-1-git-send-email-arun.thomas@gmail.com
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/cpufeature.h

@@ -114,6 +114,7 @@
 #define X86_FEATURE_CX16	(4*32+13) /* CMPXCHG16B */
 #define X86_FEATURE_XTPR	(4*32+14) /* Send Task Priority Messages */
 #define X86_FEATURE_PDCM	(4*32+15) /* Performance Capabilities */
+#define X86_FEATURE_PCID	(4*32+17) /* Process Context Identifiers */
 #define X86_FEATURE_DCA		(4*32+18) /* Direct Cache Access */
 #define X86_FEATURE_XMM4_1	(4*32+19) /* "sse4_1" SSE-4.1 */
 #define X86_FEATURE_XMM4_2	(4*32+20) /* "sse4_2" SSE-4.2 */