x86: add AMD Northbridge MSR definition

adds AMD Northbridge config MSR definition
Signed-off-by: NStephane Eranian <eranian@gmail.com>
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/asm-x86/msr-index.h

@@ -83,6 +83,7 @@
 /* AMD64 MSRs. Not complete. See the architecture manual for a more
    complete list. */
 
+#define MSR_AMD64_NB_CFG		0xc001001f
 #define MSR_AMD64_IBSFETCHCTL		0xc0011030
 #define MSR_AMD64_IBSFETCHLINAD		0xc0011031
 #define MSR_AMD64_IBSFETCHPHYSAD	0xc0011032