powerpc-utils: bump to v1.3.1, change upstream location and license

powerpc-utils: bump to v1.3.1, change upstream location and license

This patch makes below changes to powerpc-utils package:
  - Update to latest upstream version (v1.3.1)
  - Update License (from CPL to GPLv2)
  - Update source link (from SF to github)
  - Disable librtas by default
  - Finally make necessary adjustment to compile the source
    (run autogen.sh before ./configure as we don't have configure in new tarball).

RTAS:
  This package contains few tools (like nvram, ppc64_cpu, etc) which are not
  dependent on RTAS support. Traditionally we always had RTAS support (at least
  on IBM Power system). But now a days we do have environments like PowerNV host
  where we do not have RTAS support. Instead we use OPAL for runtime service [1].
  Hence lets disable RTAS by default. If someone wants to build powerpc-utils
  with RTAS they can enable it.

[1] https://github.com/open-power/skiboot.git

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[Thomas: re-add hash file, fix license, it's GPLv2+, improve commit title.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>