staging: vt6656: call vnt_update_pre_ed_threshold from vnt_config.

vnt_update_pre_ed_threshold needs to be updated more often so
call from vnt_config where it updated on any of config changes.

It must have maximum sensitivity when the device is off channel
or idle.

Remove all the other calls in scanning and bss.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Link: https://lore.kernel.org/r/1b00c112-347c-b0bb-61ed-a874ee448ff8@gmail.com


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