iwlegacy: fix IBSS cleanup

commit fa4cffcba9e13798ed7c6b8526b91b1631ecb53e upstream.

We do not correctly change interface type when switching from
IBSS mode to STA mode, that results in microcode errors.

Resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=886946

Reported-by: Jaroslav Skarvada <jskarvad@redhat.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>