Add the AMD MONITORX/MWAITX feature definition introduced in

Bulldozer/Ryzen CPUs.

Reviewed by:	kib
MFC after:	1 week

sys/x86/include/specialreg.h

@@ -227,6 +227,7 @@
 #define	AMDID2_DBE	0x04000000
 #define	AMDID2_PTSC	0x08000000
 #define	AMDID2_PTSCEL2I	0x10000000
+#define	AMDID2_MWAITX	0x20000000
 
 /*
  * CPUID instruction 1 eax info

sys/x86/x86/identcpu.c

@@ -906,7 +906,7 @@ printcpuinfo(void)
 				"\033DBE"	/* Data Breakpoint extension */
 				"\034PTSC"	/* Performance TSC */
 				"\035PL2I"	/* L2I perf count */
-				"\036<b29>"
+		       	        "\036MWAITX"	/* MONITORX/MWAITX instructions */
 				"\037<b30>"
 				"\040<b31>"
 				);