x86: coreboot: Avoid a declaration after a label

Declare the global_data pointer at the top of the file, to avoid an
error:

   arch/x86/include/asm/global_data.h:143:35: error: a label can
      only be part of a statement and a declaration is not a statement
   board/coreboot/coreboot/coreboot.c:60:2: note: in expansion of macro
      ‘DECLARE_GLOBAL_DATA_PTR’

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/coreboot/coreboot/coreboot.c b/board/coreboot/coreboot/coreboot.c
index 3b90ae7..db855c1 100644
--- a/board/coreboot/coreboot/coreboot.c
+++ b/board/coreboot/coreboot/coreboot.c
@@ -10,6 +10,8 @@
 #include <asm/cb_sysinfo.h>
 #include <asm/global_data.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 int board_early_init_r(void)
 {
 	/*
@@ -54,14 +56,12 @@
 	return 0;
 
 fallback:
-#ifdef CONFIG_OF_CONTROL
-	DECLARE_GLOBAL_DATA_PTR;
-
-	model = fdt_getprop(gd->fdt_blob, 0, "model", NULL);
+	if (IS_ENABLED(CONFIG_OF_CONTROL)) {
+		model = fdt_getprop(gd->fdt_blob, 0, "model", NULL);
 
-	if (model)
-		printf("Model: %s\n", model);
-#endif
+		if (model)
+			printf("Model: %s\n", model);
+	}
 
 	return checkboard();
 }