ARM: dts: r9a06g032: Correct UART and add all other UARTs

- UART0 was missing the bus clock ("apb_pclk").
- Use recently accepted r9a06g032 and rzn1 compat strings.
- Add all the other UARTs.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
[simon: updated changelog]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>