sunxi: video: Fix VIDEO_LCD_PANEL_I2C being enabled by default

Fix a typo in board/sunxi/Kconfig which caused VIDEO_LCD_PANEL_I2C to be
enabled on all sunxi boards. Also fix a compile error which shows up once
VIDEO_LCD_PANEL_I2C is actually disabled on most boards as it should be.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>