staging: wilc1000: linux_wlan: remove unused define CUSTOMER_PLATFORM

This patch remove unused define CUSTOMER_PLATFORM from linux_wlan.c.

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>