patch.py: Use git format-patch with --no-signature --no-numbered params
* --no-signature saves unnecessary .patch modifications when executed on
host with different git version
* --no-numbered saves unnecessary .patch modifications when number of the
applied patches is changed (the number is still in the filename so the
order how they should be applied is still preserved)
* both options exist for very long time, I've tested them with git 1.9.1
from Ubuntu 14.04 and I'm quite sure they were available even in much
older releases, so there shouldn't be any issue on relatively new sanity
tested distros
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
