config: odroid-xu3: add support for RTL8188CU

RTL8188CU is a chipset for wireless network interface which is used in
the companion USB network card hardkernel sells. It is the same as
RTL8192CU. This commit enables RTL8192CU and 802.11 wireless extension.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>