wimax: headers for kernel API and user space interaction

Definitions for the user/kernel API protocol through generic
netlink. User space can copy it verbatim and use it.

Kernel API definition declares the main data types and calls for the
drivers to integrate into the WiMAX stack. Provides usage
documentation.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>