exynos5: common: Enable CONFIG_USB_ETHER_RTL8152 ethernet support

Enable CONFIG_USB_ETHER_RTL8152 support for Odroid XU4 which
has support for RTL8153-CG gigabit Ethernet adapter,
connected over USB 3.0.

commit 9dc8ba19 added support
for Realtek 8152/8153 driver.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>