Add a EDAC driver for the RAS capabilities on the Xilinx integrated DDR
Memory Controllers (DDRMCs) which support both DDR4 and LPDDR4/4X memory
interfaces. It has four programmable Network-on-Chip (NoC) interface
ports and is designed to handle multiple streams of traffic. The driver
reports correctable and uncorrectable errors, and also creates debugfs
entries for testing through error injection.

  [ bp:
   - Add a pointer to the documentation about the register unlock code.
   - Squash in a fix for a Smatch static checker issue as reported by
     Dan Carpenter:
     https://lore.kernel.org/r/a4db6f93-8e5f-4d55-a7b8-b5a987d48a58@moroto.mountain
  ]
Co-developed-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231005101242.14621-3-shubhrajyoti.datta@amd.com