SPI mode 0 maps to the case where we have write on rising and read on
falling clock edge. Fix the OMAP2 McSPI and OMAP1 uWire edge selection
accordingly.

In the uWire case the meaning of the HW flag selecting the read edge
selection must be flipped for correct operation and this is in
contradiction with the OMAP1 specification. Tests were performed on SPI
devices using mode 1 (original uWire protocoll) like the ads7846 to
validate this.
Signed-off-by: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>