[ethernet] Skip the custom W5500 SPI driver for other ethernet types (#18533)

esphome/components/ethernet/__init__.py

@@ -811,6 +811,10 @@ _platform_filter = filter_source_files_from_platform(
             PlatformFramework.ESP32_IDF,
             PlatformFramework.ESP32_ARDUINO,
         },
+        "w5500_custom_spi.cpp": {
+            PlatformFramework.ESP32_IDF,
+            PlatformFramework.ESP32_ARDUINO,
+        },
     }
 )
 
@@ -830,6 +834,11 @@ def _filter_source_files() -> list[str]:
         # to avoid shadowing. Native IDF builds always need the custom driver.
         if cv.Version(5, 4, 2) <= idf_version() < cv.Version(6, 0, 0):
             excluded.append("esp_eth_phy_jl1101.c")
+    # The custom W5500 SPI driver is fully #ifdef'd on USE_ESP32 and
+    # USE_ETHERNET_W5500 (the platform filter map above handles non-ESP32);
+    # skip it entirely for the other ethernet types.
+    if eth_type != "W5500":
+        excluded.append("w5500_custom_spi.cpp")
     return excluded