serial: bcm6858: add serial support

This driver add the support of serial on bcm6858.
It's based on serial for bcm6345.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 03dc29e..a48458f 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -35,6 +35,7 @@
 obj-$(CONFIG_ARM_DCC) += arm_dcc.o
 obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
 obj-$(CONFIG_BCM6345_SERIAL) += serial_bcm6345.o
+obj-$(CONFIG_BCM6858_SERIAL) += serial_bcm6858.o
 obj-$(CONFIG_EFI_APP) += serial_efi.o
 obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
 obj-$(CONFIG_MCFUART) += mcfuart.o