x86/ras/mce_amd_inj: Inject bank 4 errors on the NBC

Bank 4 MCEs are logged and reported only on the node base core
(NBC) in a socket. Refer to the D18F3x44[NbMcaToMstCpuEn] field
in Fam10h and later BKDGs. The node base core (NBC) is the
lowest numbered core in the node.

This patch ensures that we inject the error on the NBC for bank
4 errors. Otherwise, triggering #MC or APIC interrupts on a core
which is not the NBC would not have any effect on the system,
i.e. we would not see any relevant output on kernel logs for the
error we just injected.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
[ Cleanup comments. ]
[ Add a missing dependency on AMD_NB caught by Randy Dunlap. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1443190851-2172-4-git-send-email-Aravind.Gopalakrishnan@amd.com
Link: http://lkml.kernel.org/r/1444641762-9437-5-git-send-email-bp@alien8.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>