ARM: brcmstb: Add debug UART entry for 72116

72116 has the same memory map as 7255 and the same physical address for
the UART, alias the definition accordingly.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>