spi: pxa2xx: Remove unused argument from pxa2xx_spi_dma_prepare()

Current DMA engine implementation of pxa2xx_spi_dma_prepare() don't use
the dma_burst argument. Remove it since it became unused after
commit 6356437e65 ("spi: spi-pxa2xx: remove legacy PXA DMA bits").

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-pxa2xx.h

@@ -139,7 +139,7 @@ extern void *pxa2xx_spi_next_transfer(struct driver_data *drv_data);
 #define DEFAULT_DMA_CR1		(SSCR1_TSRE | SSCR1_RSRE | SSCR1_TRAIL)
 
 extern irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data);
-extern int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst);
+extern int pxa2xx_spi_dma_prepare(struct driver_data *drv_data);
 extern void pxa2xx_spi_dma_start(struct driver_data *drv_data);
 extern int pxa2xx_spi_dma_setup(struct driver_data *drv_data);
 extern void pxa2xx_spi_dma_release(struct driver_data *drv_data);