buildroot

check-package: enable for arch/ and system/

These directories can benefit from this script to prevent common
mistakes when submitting patches.

In order to accomplish this:
Do not ignore anymore files from these directories.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>