ARM/arm64: dts: Rename SMB bus to just bus

Discussing the YAML validation schema with the DT maintainers
it came out that a bus named "smb@80000000" is not really
accepted, and the schema was written to name the static memory
bus just "bus@80000000".

This change is necessary for the schema to kick in and validate
these device trees, else the schema gets ignored.

Cc: Rob Herring <robh+dt@kernel.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>