linux-phytec-fsl

spi/devicetree: Move devicetree support code into spi directory

The SPI device tree support code isn't shared by any other subsystem.  It can
be moved into the core drivers/spi directory and the exported symbol can be
removed.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>