spi: spi-ep93xx: use the default master transfer queueing mechanism

Update this driver to the default implementation of transfer_one_message().

Signed-off-by: H Hartley Sweeten <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Chris Packham <[email protected]>
Signed-off-by: Mark Brown <[email protected]>

Author: bigguiness