checkpatch: fix tree recognition

With the recent rename of documentation -> Documentation, the
checkpatch.pl script broke. Fix the tree check, and change the
user visible output of "kernel" to coreboot.

Change-Id: I34f538d4436e468b1c91eb36aa2f60a2a3308111
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10125
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
1 file changed