Merge branch 'dev_get_by_index'

Ying Xue says:

====================
use appropriate APIs to get interfaces

Under rtnl_lock protection, we should use __dev_get_name/index()
rather than dev_get_name()/index() to find interface handlers
because the former interfaces can help us avoid to change interface
reference counter.

v2 changes:
 - Change return value of nl80211_set_wiphy() to 0 in patch #10
   by johannes's suggestion.
 - Add 'Acked-by' into several patches which were acknowledged by
   corresponding maintainers.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>