x86: support always running TSC on Intel CPUs, add cpufeature definition

Impact: add new synthetic-cpuid bit definition

add X86_FEATURE_NONSTOP_TSC to the cpufeature bits - this is in
preparation of Venki's always-running-TSC patch.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/cpufeature.h

@@ -92,6 +92,7 @@
 #define X86_FEATURE_AMDC1E	(3*32+21) /* AMD C1E detected */
 #define X86_FEATURE_XTOPOLOGY	(3*32+22) /* cpu topology enum extensions */
 #define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be reliable */
+#define X86_FEATURE_NONSTOP_TSC	(3*32+24) /* TSC does not stop in C states */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* "pni" SSE-3 */