package/linux-tools: some selftests needs kmod's modprobe

package/linux-tools: some selftests needs kmod's modprobe

Some kernel-selftests are using modprobe options (-n) that are not available
from busybox's modprobe, so make sure that BR2_PACKAGE_KMOD_TOOLS is selected.

[linux-4.19 selftests]$ git grep tput
drivers/gpu/drm_mm.sh:if ! /sbin/modprobe -n -q test-drm_mm; then
drivers/usb/usbip/usbip_test.sh:if ! /sbin/modprobe -q -n usbip_host; then

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>