EDAC/mce_amd: Print !SMCA processor warning only once

This warning is output for every virtual CPU in a guest on an EPYC 2
system because kvm doesn't enable SMCA. Once is enough too.

 [ bp: Massage. ]
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200217134627.19765-1-prarit@redhat.com

drivers/edac/mce_amd.c

@@ -1239,7 +1239,7 @@ static int __init mce_amd_init(void)
 
 	case 0x17:
 	case 0x18:
-		pr_warn("Decoding supported only on Scalable MCA processors.\n");
+		pr_warn_once("Decoding supported only on Scalable MCA processors.\n");
 		return -EINVAL;
 
 	default: