x86: coreboot: Show unimplemented sysinfo tags

Sometimes coreboot adds new tags that U-Boot does not know about. These
are silently ignored, but it is useful to at least know what we are
missing.

Add a way to collect this information. For Brya it shows:

   Unimpl. 38 41 37 34 42 40

These are:

   LB_TAG_PLATFORM_BLOB_VERSION
   LB_TAG_ACPI_CNVS
   LB_TAG_FMAP
   LB_TAG_VBOOT_WORKBUF
   LB_TAG_TYPE_C_INFO
   LB_TAG_BOARD_CONFIG

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/cmd/x86/cbsysinfo.c b/cmd/x86/cbsysinfo.c
index 07570b0..2b8d3b0 100644
--- a/cmd/x86/cbsysinfo.c
+++ b/cmd/x86/cbsysinfo.c
@@ -364,6 +364,14 @@
 
 	print_ptr("Chrome OS VPD", info->chromeos_vpd);
 	print_ptr("RSDP", info->rsdp);
+	printf("%-12s: ", "Unimpl.");
+	if (info->unimpl_count) {
+		for (i = 0; i < info->unimpl_count; i++)
+			printf("%02x ", info->unimpl[i]);
+		printf("\n");
+	} else {
+		printf("(none)\n");
+	}
 }
 
 static int do_cbsysinfo(struct cmd_tbl *cmdtp, int flag, int argc,