net80211: Remove tautological state display

When printing the current state name and the old state numeric value,
both are always the same. Remove the redundant ostate. It is always
the same as iv_state.

Reviewed by: bz
Differential Revision: https://reviews.freebsd.org/D35849

(cherry picked from commit 4f158a444ee7365454cc3ea1547b1b5c323dae55)