spi: intel: Fixing how speed is set

This was failing, the documentationg provides numbers only telling at
one places these are hexadecimal values. So switching to hexadecimal.
Then DDS rate retrieving macro was bogus, so fixing it.
And adding debug output about the DDS rate and the clock ratio.

Change-Id: I9cc414796fbd7f7123f1f406c6bce7ffacf641e8
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>