drivers: imx: mxc_usdhc: Do not set MMC_RSP_48 for MMC_RESPONSE_R2

commit 97d5db8c reverts an update to the
MMC layer that accompanied the original submission of this MMC driver this
is the right-thing-to-do in terms of the MMC spec.

Unfortunately the reversion also breaks this driver. The issue is the i.MX
controller doesn't want MMC_RSP_48 set for MMC_RESPONSE_R2.

The appropriate place to place that constraint is obviously in
drivers/imx/usdhc/imx_usdhc.c not in the shared MMC codebase. This patch
restores the logic the i.MX controller requires without breaking it for
everyone else.

Fixes: 97d5db8c
Fixes: 2a82a9c9

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Jun Nie <jun.nie@linaro.org>

drivers/imx/usdhc/imx_usdhc.c

@@ -160,7 +160,7 @@ static int imx_usdhc_send_cmd(struct mmc_cmd *cmd)
 		mixctl |= MIXCTRL_DMAEN;
 	}
 
-	if (cmd->resp_type & MMC_RSP_48)
+	if (cmd->resp_type & MMC_RSP_48 && cmd->resp_type != MMC_RESPONSE_R2)
 		xfertype |= XFERTYPE_RSPTYP_48;
 	else if (cmd->resp_type & MMC_RSP_136)
 		xfertype |= XFERTYPE_RSPTYP_136;