boards: nucleo_f411r: fix ram size to 128KB

Nucleo F411RE(STM32F411RET6) is provides 128 Kbytes of SRAM.

Link: https://www.st.com/en/microcontrollers-microprocessors/stm32f411re.html [1]
Link: https://docs.zephyrproject.org/latest/boards/st/nucleo_f411re/doc/index.html [2]

Signed-off-by: YongWoo Kang <kyw0708@kumoh.ac.kr>

boards/st/nucleo_f411re/nucleo_f411re.yaml

@@ -14,6 +14,6 @@ supported:
   - gpio
   - spi
   - i2c
-ram: 96
+ram: 128
 flash: 512
 vendor: st