wimax: allow specifying debug levels as command line option

Add "debug" module options to all the wimax modules (including
drivers) so that the debug levels can be set upon kernel boot or
module load time.

This is needed as currently there was a limitation where the debug
levels could only be set when a device was succesfully
enumerated. This made it difficult to debug issues that made a device
not probe properly.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>