spi/pxa2xx-pci: switch to use pcim_* interfaces

Instead of open-coding all the error management in the driver we can take
advantage of the pcim_* interfaces that release the resources automatically.

We also use platform_device_register_full() to register the platform device
because it allows us to create and register the platform device at one go,
simplifying the error management.

This a preparatory step for getting rid of pxa_ssp_request()/free() which
we will do in the next patch.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>