Adding DVI support to OMAP4 PandaBoard.

PandaBoard uses TFP410 DVI Framer chip
http://focus.ti.com/lit/ds/symlink/tfp410.pdf

The TFP410 gets its power enable and display data over GPIO lines muxed
in from OMAP4430. PandaBoard supports other LCD displays through
expansion
connectors, following board rework. This will disable the DVI interface.
However, the existing mux settings remain the same

PandaBoard additionally supports display over HDMI interface. It is
mutually exclusive to display over DVI. Hence the mux settings need to
be
configured seperately, as and when HDMI is enabled

Also, I2C3 bus used for reading EDID data from DVI Monitors is
registered here. Since the design is similar to BeagleBoard, the code
for the same is taken from the kernel.org commit e3333f48
(omap: Adding beagle i2c eeprom driver to read EDID)
Reviewed-by: Manjunath G Kondaiah <manjugk@ti.com>
Reviewed-by: Anand Gadiyar <gadiyar@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Raghuveer Murthy <raghuveer.murthy@ti.com>
[tomi.valkeinen@ti.com: fixed conflicts with HDMI]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>