staging: rtl8723bs: remove code related to unsupported channel bandwidth

remove all code related to unsupported channel
bandwidth (i.e. 80, 80+80, 160 Mhz). rtl8723bs NIC
works only on 20 and 40 Mhz channels.

Module parameter rtw_bw_mode can only have two
values: 0 and 1 (20 Mhz and 40Mhz). So modify
the default value setting to zero the 5Ghz nibble.

Comments modified accordingly.

Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/7b2ee7cc0abfd8744ed5ff4a654fb333fee77ec7.1624367071.git.fabioaiuto83@gmail.com


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