Merge pull request #2617 from bcostm/serialfc_F2

STM32F2xx - Enable Serial Flow Control

Author: sg-

hal/targets.json

@@ -704,7 +704,7 @@
         "inherits": ["Target"],
         "progen": {"target": "nucleo-f207zg"},
         "detect_code": ["0835"],
-        "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
+        "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SERIAL_FC", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
         "features": ["IPV4"],
         "release_versions": ["2", "5"]
     },