devtools: clarify that lines up to 100 characters are ok

devtools: clarify that lines up to 100 characters are ok

Since we allow line lengths of up to 100, and the CI checkpatches job
only check for that amount, the rest of our tooling and docs should
reflect this reality. Therefore we can:

* adjust the editorconfig to use that value, to save editors (e.g. vim)
  from automatically wrapping lines at 80 characters when typing.
  [Since python checkers all seem to expect 79 character lines max, add
  for python only a 79-char max line length.]

* change the default line length setting in checkpatches script to 100
  so as it matches CI and pre-merge checks.

* update the docs to clarify that while 80 chars is recommended, up to
  100 characters is acceptable.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: Jerin Jacob <jerinj@marvell.com>
Acked-by: Chenbo Xia <chenbo.xia@intel.com>
Acked-by: Chengwen Feng <fengchengwen@huawei.com>
Acked-by: Conor Walsh <conor.walsh@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>