ram: k3-ddrss: Introduce ECC Functionality for full memory space

ram: k3-ddrss: Introduce ECC Functionality for full memory space

Introduce ECC Functionality for full memory space as implemented in the
DDRSS. The following is done to accomplish this:

 * Introduce a memory region "ss" to allow dt to provide DDRSS region,
   which is not the same as "ctl" which is the controller region.

 * Introduce a "ti,ecc-enable" flag which allows a memorycontroller
   instance to enable ecc.

 * Introduce functionality to properly program the DDRSS registers to
   enable ECC for the full DDR memory space if enabled with above flag.

 * Expose a k3_ddrss_ddr_fdt_fixup call to allow fixup of fdt blob to
   account from DDR memory that must be reserved for ECC operation.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>