cmd: cat: add new command

Add cat command to print file content 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 6f00bd9..3267811 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1533,6 +1533,11 @@
 
 menu "Shell scripting commands"
 
+config CMD_CAT
+	bool "cat"
+	help
+	  Print file to standard output
+
 config CMD_ECHO
 	bool "echo"
 	default y