soldering error: flip D0 and D1 on SPI.

Signed-off-by: Nishanth Menon <nm@ti.com>
dsti-hack: make everything as input pin.

now finally we can see data inside OMAP!

Signed-off-by: Nishanth Menon <nm@ti.com>
ads79xx: do more cleanups + read twice.

For some weird reasons, looks like a double spi read is necessary
to get valid data (valid is when the Data15-12 shows the same channel
we requested conversion for)

Signed-off-by: Nishanth Menon <nm@ti.com>