cmd: xxd: add new command

Add xxd command to print file content as hexdump to standard out

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Roger Knecht <rknecht@pm.me>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 3267811..8eeb7ea 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -469,6 +469,11 @@
 	help
 	  Extract a part of a multi-image.
 
+config CMD_XXD
+	bool "xxd"
+	help
+	  Print file as hexdump to standard output
+
 config CMD_SPL
 	bool "spl export - Export boot information for Falcon boot"
 	depends on SPL