ast2400: replace ast2400 with aspeed_soc

ast2400: replace ast2400 with aspeed_soc

This is a name replacement to prepare ground for other SoCs.

Let's also remove the AST2400_SMC_BASE definition from the address
space mappings, as it is not used. This controller was removed from
the Aspeed SoC AST2500, so this provides us a better common base for
the address space mapping on both SoCs.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1473438177-26079-3-git-send-email-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>