mwifiex: reset 11h active flag when chandef does not require dfs

This patch fixes an issue where we were still setting 11h_active
flag to true for channel defs where DFS is not required.

Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>