aspeed: Add a DRAM memory region at the SoC level

aspeed: Add a DRAM memory region at the SoC level

Currently, we link the DRAM memory region to the FMC model (for DMAs)
through a property alias at the SoC level. The I2C model will need a
similar region for DMA support, add a DRAM region property at the SoC
level for both model to use.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20191119141211.25716-4-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>