stm32f7: sdram: move sdram driver code to ram drivers area

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
cc: Christophe KERELLO <christophe.kerello@st.com>
diff --git a/drivers/ram/Kconfig b/drivers/ram/Kconfig
index ff09f22..61afd7a 100644
--- a/drivers/ram/Kconfig
+++ b/drivers/ram/Kconfig
@@ -16,3 +16,11 @@
 	  If this is acceptable and you have a need to use RAM drivers in
 	  SPL, enable this option. It might provide a cleaner interface to
 	  setting up RAM (e.g. SDRAM / DDR) within SPL.
+
+config STM32_SDRAM
+	bool "Enable STM32 SDRAM support"
+	depends on RAM
+	help
+	  STM32F7 family devices support flexible memory controller(FMC) to
+	  support external memories like sdram, psram & nand.
+	  This driver is for the sdram memory interface with the FMC.