The i2c handling in tfp410 driver, which handles converting parallel RGB
to DVI, was changed in 958f2717
(OMAPDSS: TFP410: pdata rewrite). The patch changed what value the
driver considers as invalid/undefined.  Before the patch, 0 was the
invalid value, but as 0 is a valid bus number, the patch changed this to
-1.

However, the fact was missed that many board files do not define the bus
number at all, thus it's left to 0. This causes the driver to fail to
get the i2c bus, exiting from the driver's probe with an error, meaning
that the DVI output does not work for those boards.

This patch fixes the issue by changing the i2c_bus number field in the
driver's platform data from u16 to int, and setting the bus number to -1
in the board files for the boards that did not define the bus. The
exception is devkit8000, for which the bus is set to 1, which is the
correct bus for that board.

The bug exists in v3.5+ kernels.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reported-by: Thomas Weber <thomas@tomweber.eu>
Cc: Thomas Weber <thomas@tomweber.eu>
Cc: <stable@vger.kernel.org> # v3.5+
Signed-off-by: Tony Lindgren <tony@atomide.com>