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>
diff --git a/net/wimax/debugfs.c b/net/wimax/debugfs.c
index 94d216a..6c9bedb 100644
--- a/net/wimax/debugfs.c
+++ b/net/wimax/debugfs.c
@@ -61,6 +61,7 @@
 	__debugfs_register("wimax_dl_", op_msg, dentry);
 	__debugfs_register("wimax_dl_", op_reset, dentry);
 	__debugfs_register("wimax_dl_", op_rfkill, dentry);
+	__debugfs_register("wimax_dl_", op_state_get, dentry);
 	__debugfs_register("wimax_dl_", stack, dentry);
 	result = 0;
 out: