serial: mcfuart: renaming to a more appropriate name

All drivers seems to align now to serial_xxx maning, so, aligning
also this driver, to allow to be found easily.
Signed-off-by: NAngelo Durgehello <angelo.dureghello@timesys.com>

drivers/serial/Makefile

@@ -39,7 +39,7 @@ obj-$(CONFIG_COREBOOT_SERIAL) += serial_coreboot.o
 obj-$(CONFIG_CORTINA_UART) += serial_cortina.o
 obj-$(CONFIG_EFI_APP) += serial_efi.o
 obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
-obj-$(CONFIG_MCFUART) += mcfuart.o
+obj-$(CONFIG_MCFUART) += serial_mcf.o
 obj-$(CONFIG_SYS_NS16550) += ns16550.o
 obj-$(CONFIG_S5P) += serial_s5p.o
 obj-$(CONFIG_MXC_UART) += serial_mxc.o