x86/nmi: Remove edac.h include leftover

... which

  db47d5f8 ("x86/nmi, EDAC: Get rid of DRAM error reporting thru PCI SERR NMI")

forgot to remove.

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200515182246.3553-1-bp@alien8.de