boards: stm32f4_disco: Fix yaml ram size
boards: stm32f4_disco: Fix yaml ram size

Total RAM is 192, including 64K CCM.

Signed-off-by: Kwon Tae-young <44cb37ae90d26743cfd2ce90aaf3b040a10317bd@m2i.co.kr>

nashif/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,Vudentz/zephyr,ldts/zephyr,ldts/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr