ram: k3-ddrss: Use DDR address instead of system address for ecc_regions

ram: k3-ddrss: Use DDR address instead of system address for ecc_regions

Let ecc_regions[x].start reflect the start of the ECC region in terms of
DDR addressing rather than system addressing. This will make it easier
to extend the usage of the same ecc_regions structure for multi-DDR
systems as well.

Reviewed-by: Udit Kumar <u-kumar1@ti.com>
Signed-off-by: Neha Malcom Francis <n-francis@ti.com>