nl80211/cfg80211: add 5 and 10 MHz defines and wiphy flag

Add defines for 5 and 10 MHz channel width and fix channel
handling functions accordingly.

Also check for and report the WIPHY_FLAG_SUPPORTS_5_10_MHZ
capability.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
[fix spelling in comment]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Git-commit: 2f301ab29e4656af824592363039d8f6bd5a9f68
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


CRs-Fixed: 754373
Change-Id: Id0795fb95200f532589edfd8d0701c42fa27ebce
[sahn@codeaurora.org: resolve merge conflict by redefining
 WIPHY_FLAG_DFS_OFFLOAD to BIT(24) instead of BIT(22).
 WIPHY_FLAG_DFS_OFFLOAD is used internally only.]
Signed-off-by: Samuel Ahn <sahn@codeaurora.org>
Signed-off-by: Sarada Prasanna Garnayak <sgarna@codeaurora.org>