spi: pxa2xx: add missed break

The commit 7c7289a4 ("spi: pxa2xx: Default thresholds to PXA
configuration") while splitting up CE4100 code obviously missed a break
condition in one chunk. Add it here.

Looks like we have no active user of CE4100, though better to fix this later
than never.

Fixes: commit 7c7289a4 ("spi: pxa2xx: Default thresholds to PXA configuration")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>