spi: Intel spi driver fixes

- Handle the new error callback type, a ROR interrupt is irrecoverable.
- Removing the fifo pre-fill: this should never be done that way. It's
  up to the controller to request via an interrupt to get its fifo
  filled-in. (TFS bit on SSSR register is the one requesting such
  filling)
- Disabling the controller once completed (following transfer will
  re-enable it)
- Removing useless debugging info

Change-Id: I466a8efb65a41f3315a6a36e10ea519d0c4b01e9
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>