at91_mci: Fix byte mode transitions.

The byte mode support fails to clear the byte mode bit in the command
register, possibly leaving byte mode enabled with the counters programmed
in non-byte mode.
Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/at91_mci.c

@@ -579,7 +579,7 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
 		ier = AT91_MCI_CMDRDY;
 	} else {
 		/* zero block length and PDC mode */
-		mr = at91_mci_read(host, AT91_MCI_MR) & 0x7fff;
+		mr = at91_mci_read(host, AT91_MCI_MR) & 0x5fff;
 		mr |= (data->blksz & 0x3) ? AT91_MCI_PDCFBYTE : 0;
 		mr |= (block_length << 16);
 		mr |= AT91_MCI_PDCMODE;