package/sysdig: use kernel-module helper

sysdig's Makefile was already calling the Linux buildsystem to build its
modules, so switch to using the new kernel-module infra.

This has the benefit of making sysdig actually buildable, otherwise it
fails because it tries to use the kernel headers from the host:

    make: *** /lib/modules/3.13.0-53-generic/build: No such file or directory.  Stop.
    make[5]: *** [all] Error 2
    make[4]: *** [driver/CMakeFiles/driver] Error 2
    make[3]: *** [driver/CMakeFiles/driver.dir/all] Error 2

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>