staging: wilc1000: rename u8WLANChannel variable

This patch renames u8WLANChannel variable to wlan_channel to avoid camelcase.
And, remove the relation comment.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>