ethernet: fix some bugs in phy&mac driver

1. Original register mapping for LAN8720 has some registers that doesn't exist/support.
So just remove them, and fix the power and init function for LAN8720.
2. GPIO16 and GPIO17 is occupied by PSRAM, so only ETH_CLOCK_GPIO_IN mode is supported in that case if using PSRAM.
3. Fix bug of OTA failing with Ethernet
4. Fix bug of multicast with Ethernet
5. Fix potential memory leak

components/esp32/include/esp_spiram.h

@@ -56,7 +56,7 @@ void esp_spiram_init_cache();
 
 /**
  * @brief Memory test for SPI RAM. Should be called after SPI RAM is initialized and
- * (in case of a dual-core system) the app CPU is online. This test overwrites the 
+ * (in case of a dual-core system) the app CPU is online. This test overwrites the
  * memory with crap, so do not call after e.g. the heap allocator has stored important
  * stuff in SPI RAM.
  *
@@ -102,4 +102,14 @@ void esp_spiram_writeback_cache();
 esp_err_t esp_spiram_reserve_dma_pool(size_t size);
 
 
+/**
+ * @brief If SPI RAM(PSRAM) has been initialized
+ *
+ * @return
+ *          - true SPI RAM has been initialized successfully
+ *          - false SPI RAM hasn't been initialized or initialized failed
+ */
+bool esp_spiram_is_initialized(void);
+
+
 #endif