ram: k3-ddrss: add auto-generated macros for am62a support

The new 32bit DDR controller for TI's am62a family of SoCs shares much
of the same functionality with the existing 16bit (am64) and 32bit
(j721e) controllers, so this patch reorganizes the existing
auto-generated macros for the 16bit and 32bit controllers to make room
for the macros for the am62a's controller

This patch consists mostly of header/macro renames and additions with a
new Kconfig option (K3_AM62A_DDRSS) allowing us to select these new
macros during compilation.

Signed-off-by: Bryan Brattlof <bb@ti.com>