tty: serial: bcm63xx_uart: add support for DT probing

Add a matching table for the the bcm63xx_uart driver on the compatible
string "brcm,bcm6345-uart" which covers all BCM63xx implementations and
reflects the fact that this block was first introduced with the BCM6345
SoC.  Also make sure that we convert the id based on the uart aliases
provided by the relevant Device Tree.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>