efi_loader: Use %pD to log device-path instead of local efi_dp_str()

Use %pD to log device-path instead of using efi_dp_str() and
efi_free_pool() locally in find_boot_device().
This is a cleanup patch, no feature update nor fix.
Suggested-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu@linaro.org>
Reviewed-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>

lib/efi_loader/efi_capsule.c

@@ -691,11 +691,7 @@ skip:
 	}
 found:
 	if (boot_dev) {
-		u16 *path_str;
-
-		path_str = efi_dp_str(boot_dev);
-		log_debug("Boot device %ls\n", path_str);
-		efi_free_pool(path_str);
+		log_debug("Boot device %pD\n", boot_dev);
 
 		volume = efi_fs_from_path(boot_dev);
 		if (!volume)