mmc: mmci: Add private pointer for variant

In variant init function, some references may be allocated for variant
specific usage. Add a private void* to mmci_host struct allows at variant
functions to access on this references by mmci_host structure.
Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Link: https://lore.kernel.org/r/20200128090636.13689-5-ludovic.barre@st.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mmci.h

@@ -410,6 +410,7 @@ struct mmci_host {
 	struct mmc_host_ops	*mmc_ops;
 	struct mmci_host_ops	*ops;
 	struct variant_data	*variant;
+	void			*variant_priv;
 	struct pinctrl		*pinctrl;
 	struct pinctrl_state	*pins_opendrain;