treewide: fdt: Move fdt_get_config_... to ofnode_conf_read...

The current API is outdated as it requires a devicetree pointer.

Move these functions to use the ofnode API and update this globally. Add
some tests while we are here.

Correct the call in exynos_dsim_config_parse_dt() which is obviously
wrong.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/cli.c b/common/cli.c
index 048eacb..d86046a 100644
--- a/common/cli.c
+++ b/common/cli.c
@@ -19,8 +19,7 @@
 #include <hang.h>
 #include <malloc.h>
 #include <asm/global_data.h>
-
-DECLARE_GLOBAL_DATA_PTR;
+#include <dm/ofnode.h>
 
 #ifdef CONFIG_CMDLINE
 /*
@@ -157,7 +156,7 @@
 bool cli_process_fdt(const char **cmdp)
 {
 	/* Allow the fdt to override the boot command */
-	char *env = fdtdec_get_config_string(gd->fdt_blob, "bootcmd");
+	const char *env = ofnode_conf_read_str("bootcmd");
 	if (env)
 		*cmdp = env;
 	/*
@@ -165,7 +164,7 @@
 	 * Always use 'env' in this case, since bootsecure requres that the
 	 * bootcmd was specified in the FDT too.
 	 */
-	return fdtdec_get_config_int(gd->fdt_blob, "bootsecure", 0) != 0;
+	return ofnode_conf_read_int("bootsecure", 0);
 }
 
 /*