EDAC/igen6: Add EDAC driver for Intel client SoCs using IBECC

commit 10590a9d

 upstream.

This driver supports Intel client SoC with integrated memory controller
using In-Band ECC(IBECC). The memory correctable and uncorrectable errors
are reported via NMIs. The driver handles the NMIs and decodes the memory
error address to platform specific address. The first IBECC-supported SoC
is Elkhart Lake.

[Tony: s/#include <linux/nmi.h>/#include <asm/nmi.h>/ to fix randconfig build]

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Liwei Song <liwei.song@windriver.com>