When given a relative path to the kernel git tree,
update-kernel-headers.sh fails to execute the headers_install.sh script
from the kernel sources. Fix it by turning the kernel directory into an
absolute path.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>