axfsutils: add new package

Tools for building AXFS Filesystem.

The Advanced XIP File System is a Linux kernel filesystem driver that
enables files to be executed directly from flash or ROM memory rather
than being copied into RAM. It has the ability to store individual
*pages* in a file uncompressed/XIP or compressed/Demand Paged.

Source:
	https://github.com/jaredeh/axfs



[Thomas:
 - add hash file.
 - use $(INSTALL) -D -m 0755 instead of cp for installing mkfs.axfs.]

Signed-off-by: Ariel D'Alessandro <ariel@vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>