stm32f7: remove not needed configuration from board config

This patch removes:
	- CONFIG_CMD_MEM: enabled by default
	- CONFIG_DESIGNWARE_ETH : not being used anywhere.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
cc: Christophe KERELLO <christophe.kerello@st.com>

include/configs/stm32f746-disco.h

@@ -28,7 +28,6 @@
 #define CONFIG_STM32_FLASH
 #define CONFIG_STM32X7_SERIAL
 
-#define CONFIG_DESIGNWARE_ETH
 #define CONFIG_DW_GMAC_DEFAULT_DMA_PBL	(8)
 #define CONFIG_DW_ALTDESCRIPTOR
 #define CONFIG_MII
@@ -67,8 +66,6 @@
 #define CONFIG_SYS_LONGHELP
 #define CONFIG_AUTO_COMPLETE
 #define CONFIG_CMDLINE_EDITING
-
-#define CONFIG_CMD_MEM
 #define CONFIG_CMD_CACHE
 #define CONFIG_BOARD_LATE_INIT
 #define CONFIG_DISPLAY_BOARDINFO