staging: rtl8723bs: remove rtw_hal_is_disable_sw_channel_plan

Remove function rtw_hal_is_disable_sw_channel_plan because it is not
used.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Link: https://lore.kernel.org/r/4398fec06b0f8defaa7da9d6abbc155cbb7ae630.1662111799.git.namcaov@gmail.com


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