spi: atmel: add WDRBT bit to avoid receive overrun

The atmel at91sam9x5 series spi has feature to avoid receive overren

Using the patch to enable it

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/drivers/spi/atmel_spi.h b/drivers/spi/atmel_spi.h
index 8b69a6d..057de9a 100644
--- a/drivers/spi/atmel_spi.h
+++ b/drivers/spi/atmel_spi.h
@@ -26,6 +26,7 @@
 #define ATMEL_SPI_MR_PCSDEC		(1 << 2)
 #define ATMEL_SPI_MR_FDIV		(1 << 3)
 #define ATMEL_SPI_MR_MODFDIS		(1 << 4)
+#define ATMEL_SPI_MR_WDRBT		(1 << 5)
 #define ATMEL_SPI_MR_LLB		(1 << 7)
 #define ATMEL_SPI_MR_PCS(x)		(((x) & 15) << 16)
 #define ATMEL_SPI_MR_DLYBCS(x)		((x) << 24)