arm: socfpga: Move Stratix10 and Agilex to use TARGET_SOCFPGA_SOC64

Create common macro TARGET_SOCFPGA_SOC64 for Stratix10 and Agilex.

Signed-off-by: Siew Chin Lim <elly.siew.chin.lim@intel.com>
diff --git a/drivers/ddr/altera/Kconfig b/drivers/ddr/altera/Kconfig
index 8f590dc..4660d20 100644
--- a/drivers/ddr/altera/Kconfig
+++ b/drivers/ddr/altera/Kconfig
@@ -1,8 +1,8 @@
 config SPL_ALTERA_SDRAM
 	bool "SoCFPGA DDR SDRAM driver in SPL"
 	depends on SPL
-	depends on TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_ARRIA10 || TARGET_SOCFPGA_STRATIX10 || TARGET_SOCFPGA_AGILEX
-	select RAM if TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_STRATIX10 || TARGET_SOCFPGA_AGILEX
-	select SPL_RAM if TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_STRATIX10 || TARGET_SOCFPGA_AGILEX
+	depends on TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_ARRIA10 || TARGET_SOCFPGA_SOC64
+	select RAM if TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_SOC64
+	select SPL_RAM if TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_SOC64
 	help
 	  Enable DDR SDRAM controller for the SoCFPGA devices.