spi: pxa2xx-pci: Drop unused header inclusion

There is nothing in the driver which requires OF specific header
to be included.

Remove it for good.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-pxa2xx-pci.c

@@ -5,7 +5,6 @@
  */
 #include <linux/clk-provider.h>
 #include <linux/module.h>
-#include <linux/of_device.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/spi/pxa2xx_spi.h>