configs: stm32f429-disco: Remove CONFIG_SYS_RAM_CS

This flag is not used, remove it.
Signed-off-by: NPatrice Chotard <patrice.chotard@st.com>

include/configs/stm32f429-discovery.h

@@ -20,7 +20,6 @@
  * Configuration of the external SDRAM memory
  */
 #define CONFIG_NR_DRAM_BANKS		1
-#define CONFIG_SYS_RAM_CS		1
 #define CONFIG_SYS_RAM_FREQ_DIV		2
 #define CONFIG_SYS_LOAD_ADDR		0x90400000
 #define CONFIG_LOADADDR			0x90400000