MIPS: BCM63xx: Add support for second uart.

The BCm63xx SOC has two uarts.  Some boards use the second one for
bluetooth.  This patch changes platform device registration code to
handle this.  Changes to the UART driver were already merged in
6a2c7eab

.

Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
To: linux-mips@linux-mips.org
Cc: Maxime Bizon <mbizon@freebox.fr>
Patchwork: http://patchwork.linux-mips.org/patch/900/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>