Add PL2303 serial port support

Change-Id: I783e8511299e06d8a4ab1f5b9920bfc045f120a3
diff --git a/arch/arm/configs/gfrg200_defconfig b/arch/arm/configs/gfrg200_defconfig
index c60c194..42eb8ea 100644
--- a/arch/arm/configs/gfrg200_defconfig
+++ b/arch/arm/configs/gfrg200_defconfig
@@ -251,6 +251,10 @@
 CONFIG_USB_DEVICEFS=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_STORAGE=y
+CONFIG_USB_SERIAL=y
+CONFIG_USB_SERIAL_CONSOLE=y
+CONFIG_USB_SERIAL_GENERIC=y
+CONFIG_USB_SERIAL_PL2303=y
 CONFIG_RTC_CLASS=y
 # CONFIG_RTC_HCTOSYS is not set
 # CONFIG_RTC_INTF_SYSFS is not set