ARM: dts: am335x-evmsk: enable display and lcd panel support

ARM: dts: am335x-evmsk: enable display and lcd panel support

Add the necessary nodes to enable the LCD controller and the
LCD panel that is attached to the Texas Instruments AM335x
EVMSK platform.  Also setup the necessary pin mux within the
DT file to drive the LCD connector and add the correct
pinmux settings for the lcd pins to be configured to when
the SoC goes into sleep state for the minimum power
consumption.

For the sleep mode LCD pin settings, MUX_MODE7 is chosen as
this corresponds to switching the pins into input GPIO's with
an internal pulldown.  Which has been determined to offer the
lowest power solution vs leaving the pins configured in LCD
mode.

Signed-off-by: Darren Etheridge <detheridge@ti.com>
Acked-by: Wolfram Sang <wsa@sang-engineering.com>
Tested-by: Felipe Balbi <balbi@ti.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>