mmc: mmci: Send a CMD12 to clear the DPSM at errors

The current approach with sending a CMD12 (STOP_TRANSMISSION) to complete a
data transfer request, either because of using the open-ended transmission
type or because of receiving an error during a pre-defined data transfer,
isn't sufficient for the STM32 sdmmc variant. More precisely, this variant
needs to clear the DPSM ("Data Path State Machine") by sending a CMD12, for
all failing ADTC commands.

Support this, by adding a struct mmc_command inside the struct mmci_host
and initialize it to a CMD12 during ->probe(). Let's also add checks for
the new conditions, to enable mmci_data_irq() and mmci_cmd_irq() to
postpone the calls to mmci_request_end(), but instead send the CMD12.

Cc: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Ludovic Barre <ludovic.barre@st.com>
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 2422909..14df810 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -377,6 +377,7 @@
 	void __iomem		*base;
 	struct mmc_request	*mrq;
 	struct mmc_command	*cmd;
+	struct mmc_command	stop_abort;
 	struct mmc_data		*data;
 	struct mmc_host		*mmc;
 	struct clk		*clk;