staging: r8188eu: Remove code related to unsupported channels

Remove all code related to unsupported channel
bandwidths. rtl8188eu* NICs work only on 20 and
40 Mhz channels.

Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210812002519.23678-3-fmdefrancesco@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>