tools: bootconfig: Add bootconfig command

Add "bootconfig" command which operates the bootconfig
config-data on initrd image.

User can add/delete/verify the boot config on initrd
image using this command.

e.g.
Add a boot config to initrd image
 # bootconfig -a myboot.conf /boot/initrd.img

Remove it.
 # bootconfig -d /boot/initrd.img

Or verify (and show) it.
 # bootconfig /boot/initrd.img

Link: http://lkml.kernel.org/r/157867223582.17873.14342161849213219982.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ Removed extra blank line at end of bootconfig.c ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 8597285..0600500 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15775,6 +15775,7 @@
 S:	Maintained
 F:	lib/bootconfig.c
 F:	include/linux/bootconfig.h
+F:	tools/bootconfig/*
 
 SUN3/3X
 M:	Sam Creasey <sammy@sammy.net>