hw_features: Fix check of supported 802.11ac channel width

hw_features: Fix check of supported 802.11ac channel width

The two channel width bits in the VHT capability field can be decoded in
following values (IEEE Std 802.11ac-2013 8.4.2.160.2 VHT Capabilities
Info field):

 * 0: no 160 or 80+80 MHz support
 * 1: 160 MHz support
 * 2: 160 and 80+80 MHz support
 * 3: (reserved)

The check must therefore not be done bitwise but instead it must checked
whether the capabilities announced by the driver are at least the ones
requested by the user.

Fixes: c781eb842852 ("hostapd: Verify VHT capabilities are supported by driver")
Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>