image: Use constants for 'required' and 'key-name-hint'

These are used in multiple places so update them to use a shared #define.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/tools/image-host.c b/tools/image-host.c
index dfea48e..4e57dde 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -170,7 +170,7 @@
 
 	memset(info, '\0', sizeof(*info));
 	info->keydir = keydir;
-	info->keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info->keyname = fdt_getprop(fit, noffset, FIT_KEY_HINT, NULL);
 	info->fit = fit;
 	info->node_offset = noffset;
 	info->name = strdup(algo_name);
@@ -249,7 +249,7 @@
 	free(value);
 
 	/* Get keyname again, as FDT has changed and invalidated our pointer */
-	info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info.keyname = fdt_getprop(fit, noffset, FIT_KEY_HINT, NULL);
 
 	/*
 	 * Write the public key into the supplied FDT file; this might fail
@@ -337,7 +337,7 @@
 	info->keydir = keydir;
 
 	/* Read the key name */
-	info->keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info->keyname = fdt_getprop(fit, noffset, FIT_KEY_HINT, NULL);
 	if (!info->keyname) {
 		printf("Can't get key name for cipher '%s' in image '%s'\n",
 		       node_name, image_name);
@@ -886,7 +886,7 @@
 	free(region_prop);
 
 	/* Get keyname again, as FDT has changed and invalidated our pointer */
-	info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info.keyname = fdt_getprop(fit, noffset, FIT_KEY_HINT, NULL);
 
 	/* Write the public key into the supplied FDT file */
 	if (keydest) {