staging: wilc1000: rename u8ChNum of host_int_set_mac_chnl_num

This patch replaces u8ChNum with channel that is second argument of
host_int_set_mac_chnl_num to avoid camelcase.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>