fast_uart: Only build the driver when it is enabled

Change-Id: I980724b7c336f6fe012c064db4da912b14fcc2d5
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 7c6a1b6..4ff524c 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -18,7 +18,7 @@
 	default y
 	bool "i.MX serial driver"
 
-config DRIVER_FAST_UART
+config DRIVER_SERIAL_FAST_UART
 	depends on ARCH_COMCERTO
 	default y
 	bool "Comcerto Fast UART driver"
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index e90a5ef..3438626 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -17,6 +17,4 @@
 obj-$(CONFIG_DRIVER_SERIAL_PL010)		+= serial_pl010.o
 obj-$(CONFIG_DRIVER_SERIAL_S3C24X0)		+= serial_s3c24x0.o
 obj-$(CONFIG_DRIVER_SERIAL_ALTERA)		+= serial_altera.o
-#obj-$(CONFIG_DRIVER_SERIAL_FAST_UART)		+= fast_uart.o
-#FIXME: No one is setting the CONFIG_DRIVER_SERIAL_FAST_UART. It's not defined in Kconfig also.Need to be fixed
-obj-y		+= fast_uart.o
+obj-$(CONFIG_DRIVER_SERIAL_FAST_UART)		+= fast_uart.o