test: Add more SMBIOS data to sandbox

Some common smbios settings are not included with sandbox. Add these to
test.dts so the data is more meaningful.

Update smbios tests to match the new devicetree values.

Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/dts/test.dts

@@ -1938,6 +1938,30 @@
 
 	sysinfo {
 		compatible = "sandbox,sysinfo-sandbox";
+
+		smbios {
+			/* Type 1 table */
+			system {
+				manufacturer = "Sandbox Corp";
+				product = "Sandbox Computer";
+				version = "1.0";
+				serial = "SB12345678";
+				sku = "SANDBOX-SKU";
+				family = "Sandbox_Family";
+			};
+
+			/* Type 2 table */
+			baseboard {
+				manufacturer = "Sandbox Boards";
+				product = "Sandbox Motherboard";
+				asset-tag = "SB-ASSET-001";
+			};
+
+			/* Type 3 table */
+			chassis {
+				manufacturer = "Sandbox Chassis Inc";
+			};
+		};
 	};
 
 	sysinfo-gpio {