checkpatch.pl: check for openocd tree, not for kernel tree

checkpatch.pl: check for openocd tree, not for kernel tree

checkpatch.pl looks for linux kernel specific paths and files
to check source tree. As openocd misses kernel files it ends
with this error message:

    Must be run from the top-level dir. of a kernel tree

This patch also renames 'kernel' -> 'openocd'
in source tree-related messages.

Due to checkpatch checking modifications on itself, lift the
restriction on having no spaces at the start of a line for Perl
scripts. This can be readded back later.

Change-Id: I89b7ca976bef5e13785bd3a43e597c9feb4c2df4
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Reviewed-on: http://openocd.zylin.com/2339
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>