spi: pxa2xxx: change "no DMA channels..." msg from debug to warning

Change the type of the diagnostic message:

"no DMA channels available, using PIO"

from debug to warning.

The lack of an available DMA channel is very important regard the
spi-pxa2xx performance. The transfer speed can be reduced more than 50%.

So it is very important to warn the user about this, without enabling
the full SPI debug with CONFIG_SPI_DEBUG.

Moreover, enabling the full SPI debug only to enable this specific
debug message, the dmesg buffer fills quickly with a lot of
repetitive information during the SPI data transfer.
This cause the loss of all the first important messages
written during the initialization.

Signed-off-by: Flavio Suligoi <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-pxa2xx.c

···
 	if (platform_info->enable_dma) {
 		status = pxa2xx_spi_dma_setup(drv_data);
 		if (status) {
-			dev_dbg(dev, "no DMA channels available, using PIO\n");
+			dev_warn(dev, "no DMA channels available, using PIO\n");
 			platform_info->enable_dma = false;
 		} else {
 			controller->can_dma = pxa2xx_spi_can_dma;