imx9: scmi: Get DDR size through SM SCMI API

System Manager(SM) has implemented the MISC protocol to retrieve DDR
information. Using this API, U-Boot can obtain the DDR size dynamically
instead of relying on static configuration macros.

This change addresses the DDR ECC enabled case, where 1/8 of the total
DDR size is reserved for ECC data. The scmi_misc_ddrinfo() returns the
DDR size with EEC overhead already deducted.

Implementation details:
- Query the DDR size via scmi_misc_ddrinfo()
- Replace direct REG_DDR_CS[0,1]_BNDS register reads with SCMI call
- Switch from PHYS_SDRAM[x]_SIZE macros to runtime detection
- For backward compatibility with older SM firmware, fall back to
  static PHYS_SDRAM[x]_SIZE configuration if the SCMI call fails

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Alice Guo <alice.guo@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>

include/scmi_protocols.h

@@ -54,7 +54,8 @@ enum scmi_discovery_id {
 };
 
 enum scmi_imx_misc_message_id {
-	SCMI_MISC_ROM_PASSOVER_GET = 0x7
+	SCMI_MISC_ROM_PASSOVER_GET = 0x7,
+	SCMI_MISC_DDR_INFO_GET = 0x22,
 };
 
 /*