spi/atmel: typo in debug message

This patches a typo in the debug message.

Signed-off-by: Matthias Brugger <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

drivers/spi/atmel_spi.c

···
 			bits = (asd->csr >> 4) & 0xf;
 			if (bits != xfer->bits_per_word - 8) {
 				dev_dbg(&spi->dev, "you can't yet change "
-					 "bit_per_word in transfers\n");
+					 "bits_per_word in transfers\n");
 				return -ENOPROTOOPT;
 			}
 		}