stm32mp1: add sdmmc2 driver

This driver is for the STMicroelectronics sdmmc2 IP
which is in STM32MP1 SoC.
It uses the MMC framework, and can address either eMMC or SD-card.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/plat/st/stm32mp1/stm32mp1_def.h b/plat/st/stm32mp1/stm32mp1_def.h
index bb3fecf..2224498 100644
--- a/plat/st/stm32mp1/stm32mp1_def.h
+++ b/plat/st/stm32mp1/stm32mp1_def.h
@@ -155,10 +155,9 @@
 #define STM32MP1_SDMMC2_BASE		U(0x58007000)
 #define STM32MP1_SDMMC3_BASE		U(0x48004000)
 
-#define STM32MP1_SD_INIT_FREQ			400000		/*400 KHz*/
+#define STM32MP1_MMC_INIT_FREQ			400000		/*400 KHz*/
 #define STM32MP1_SD_NORMAL_SPEED_MAX_FREQ	25000000	/*25 MHz*/
 #define STM32MP1_SD_HIGH_SPEED_MAX_FREQ		50000000	/*50 MHz*/
-#define STM32MP1_EMMC_INIT_FREQ			STM32MP1_SD_INIT_FREQ
 #define STM32MP1_EMMC_NORMAL_SPEED_MAX_FREQ	26000000	/*26 MHz*/
 #define STM32MP1_EMMC_HIGH_SPEED_MAX_FREQ	52000000	/*52 MHz*/