x86, cpufeature: Add feature bit for SMAP

Add CPUID feature bit for Supervisor Mode Access Prevention (SMAP).
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/n/tip-ethzcr5nipikl6hd5q8ssepq@git.kernel.org

arch/x86/include/asm/cpufeature.h

@@ -209,6 +209,7 @@
 #define X86_FEATURE_RTM		(9*32+11) /* Restricted Transactional Memory */
 #define X86_FEATURE_RDSEED	(9*32+18) /* The RDSEED instruction */
 #define X86_FEATURE_ADX		(9*32+19) /* The ADCX and ADOX instructions */
+#define X86_FEATURE_SMAP	(9*32+20) /* Supervisor Mode Access Prevention */
 
 #if defined(__KERNEL__) && !defined(__ASSEMBLY__)