i.MX6: utc: Add recent updates from Nitrogen6x:

Include support for the following commits:
	bf3bfa46 - Add qvga panel
	804e9e9c - Add i2c edid command
        57777f8d - Add 1280x800 JEIDA panel
        b792d7da - Add splash screen support
        305db419 - Always configure RGB pads
        f0b34f59 - Configure SDIO pads
        362aa17a - Place HDMI on IPU0:DI0
        a377f7d6 - Add CONFIG_CMD_MEMTEST
        cb46e967 - Use i2cdetect for HDMI/DVI detection
        4a4fc304 - Add environment variables for devicetree
        30b4becf - Fix bug in board_video_skip
        2e0470fa - Enable USB Host
        d7a58405 - Add enable_cko1() routine

Also removed setup_buttons() since this board has no GPIO keys.

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>