configs: odroid-c4: update for HDMI output background & USB keyboard

Enable options SYS_WHITE_ON_BLACK to permit HDMI background
screen from white to back, also enable USB_KEYBOARD.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>