staging: vt6655: Remove unused byRFType in channel.c

Remove byRFType that support 5GHz band.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/3724590188e72e8f531fe03c2821c5d3d08e2e29.1646512837.git.philipp.g.hortmann@gmail.com


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