ARM: dts: aspeed: Update watchdog compatible strings

The string was changed when upstreaming the driver. Put the correct
string for generation 4 and 5 systems, as well as fix the reg length for
ast2500 systems.

Acked-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
2 files changed