spi: pxa2xx-pci: Support both chipselects on Braswell

The commit 30f3a6ab ("spi: pxa2xx: Add support for both chip selects on
Intel Braswell") introduces a support of chipselects for Intel Braswell SPI
host controller. Though it missed to convert the PCI part of the driver.

Do conversion here which enables both chipselects on Intel Braswell when
enumerated via PCI.

We don't care about num_chipselect value since it is overrided inside core
driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>