wimax: document why wimax_msg_*() operations can be used in any state

Funcion documentation for wimax_msg_alloc() and wimax_msg_send() needs
to clarify that they can be used in the very early stages of a
wimax_dev lifecycle.

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