Fix invalid frequency issues and issues with HE supporting/only AP's

This patch fixes fixes issues trying to scan some 802.11ax points
related to HE capabilities and some channel definitions/conversions.

In doing so, we add support for 802.11ax HE capabilities.
It also updates error handling to try to ensure future unhandled
frequencies or bugs will not crash the kernel.

Signed-off-by: Daniel Berlin <[email protected]>

Author: dberlin