wimax: Add netlink interface to get device state

wimax connection manager / daemon has to know what is current
state of the device. Previously it was only possible to get
notification whet state has changed.

Note:

 By mistake, the new generic netlink's number for
 WIMAX_GNL_OP_STATE_GET was declared inserting into the existing list
 of API calls, not appending; thus, it'd break existing API.

 Fixed by Inaky Perez-Gonzalez <inaky@linux.intel.com> by moving to
 the tail, where we add to the interface, not modify the interface.

 Thanks to Stephen Hemminger <shemminger@vyatta.com> for catching this.

Signed-off-by: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>

include/linux/wimax.h

@@ -78,6 +78,7 @@ enum {
 	WIMAX_GNL_OP_RFKILL,	/* Run wimax_rfkill() */
 	WIMAX_GNL_OP_RESET,	/* Run wimax_rfkill() */
 	WIMAX_GNL_RE_STATE_CHANGE,	/* Report: status change */
+	WIMAX_GNL_OP_STATE_GET,		/* Request for current state */
 };
 
 
@@ -113,6 +114,10 @@ enum {
 	WIMAX_GNL_RESET_IFIDX = 1,
 };
 
+/* Atributes for wimax_state_get() */
+enum {
+	WIMAX_GNL_STGET_IFIDX = 1,
+};
 
 /*
  * Attributes for the Report State Change