package/rng-tools: bump to 6.7

package/rng-tools: bump to 6.7

* Switch to new site and add license file hash
* Add new libsysfs dependency for rng available check
* Remove patch adding special return code when no RNG module is available.
  This has been replaced by using the jitter library to always have a
  source (new jitterentropy dependency)
* Change to a autotools build and add patch to allow README file to not be
  found during autoreconfig

Cc: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Tested-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>