omap3: spi: Correct ti, pindir-d0-out-d1-in parsing

The ti,pindir-d0-out-d1-in property is not expected to have a value
according to the device-tree binding, so treat it as a boolean not a
uint property.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Jagan Teki <jagan@openedev.com>