cfg80211: Dynamic channel bandwidth changes in AP mode

This extends NL80211_CMD_SET_CHANNEL to allow dynamic channel bandwidth
changes in AP mode (including P2P GO) during a lifetime of the BSS. This
can be used to implement, e.g., HT 20/40 MHz co-existence rules on the
2.4 GHz band.

Git-commit: e16821bcfb364b0c41142db275dc74b39fa42c30
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Change-Id: I4f325d335b6549c3483da6cfaf3d1f5ba6e610fc
CRs-fixed: 639836
Signed-off-by: Peng Xu <pxu@codeaurora.org>