ARM: dts: broadcom: Add BCM63138's high speed UART

It's designed for hardwiring Bluetooth devices to it.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20231122144208.21114-2-zajec5@gmail.com


Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>