Remove SERIAL_FC from the ARM_IOTSS_BEID

The ARM_IOTSS_BEID does not support flow control in its serial driver so it
should not have SERIAL_FC in device_has.

Author: c1728p9

targets/targets.json

@@ -4990,7 +4990,6 @@
             "PORTINOUT",
             "PORTOUT",
             "SERIAL",
-            "SERIAL_FC",
             "SPI",
             "SPISLAVE",
             "TSC",
@@ -5014,7 +5013,6 @@
             "PORTINOUT",
             "PORTOUT",
             "SERIAL",
-            "SERIAL_FC",
             "SPI",
             "SPISLAVE",
             "TSC",