The SPI polling loop timeout only works with HZ=100 as the loop was
actually too short.

Also add appropriate cpu_relax() in the busy wait loops...
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NFeng Tang <feng.tang@intel.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>