kmod: adjust license info based on kmod tools selection

The libkmod is licensed as LGPL, while the kmod tools are GPL.
We always install libkmod, but conditionally install the tools.
This patch adjusts the license variables accordingly.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>