UPSTREAM: tools/bootconfig: Show bootconfig compact tree from bootconfig file

Show the bootconfig compact tree from the bootconfig file
instead of an initrd if the given file has no magic number
and is smaller than 32KB.

User can use this for checking the syntax error or output
checking before applying the bootconfig to initrd.

Link: https://lkml.kernel.org/r/159704848156.175360.6621139371000789360.stgit@devnote2



Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
(cherry picked from commit d052e1c6)
Signed-off-by: Devin Moore <devinmoore@google.com>
Change-Id: Ie301303cab2487adb701ceba84efb9ccb2731b23