scripts: update checkpatch to latest from the linux kernel

This takes the linux diffs between
a8c964eacb21288b2dbfa9d80cee5968a3b8fb21 and
16fbf79b0f83bc752cee8589279f1ebfe57b3b6e and applies them to the
Zephyr copy.  Three changes did not apply cleanly:

* linux added a comment to the line that enables C99 comments;
  Zephyr disallows them.
* linux uses vendor-prefixes.yaml; zephyr uses the older .txt file
* manual addition of colon in a check before BRACKET_SPACE error

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>