arm64: dts: n5x: drop invalid property and fix edac node name

The intel,sysmgr-syscon in EDAC/memory controller node is not a
recognized and documented property, so drop it to fix error:

  sdr_edac@f87f8000: 'intel,sysmgr-syscon' does not match any of the regexes: 'pinctrl-[0-9]+'

Align also the node name with Devicetree specification (generic, not
specific, and EDAC is purely Linux term).

Fixes: ef82c9be ("arm64: dts: n5x: add sdr edac support")
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20220318121044.108750-1-krzysztof.kozlowski@canonical.com'
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

arch/arm64/boot/dts/intel/socfpga_n5x_socdk.dts

@@ -26,11 +26,10 @@
 	};
 
 	soc {
-		sdram_edac: sdr_edac@f87f8000 {
+		sdram_edac: memory-controller@f87f8000 {
 			compatible = "snps,ddrc-3.80a";
 			reg = <0xf87f8000 0x400>;
 			interrupts = <0 175 4>;
-			intel,sysmgr-syscon = <&sysmgr 0xb8>;
 			status = "okay";
 		};
 	};