Fixed memory leak in emac_esp_new_dma function.
Polished ESP EMAC cache management.
Added emac_periph definitions based on SoC features and improved(generalized) ESP EMAC GPIO
initialization.
Added ESP EMAC GPIO reservation.
Added check for frame error condition indicated by EMAC DMA and created a target test.
Fix dependency tree so that lwip doesn't depend on any specific network
interface component.
Network interface drivers shall depend on esp_netif.
esp_netif shall depend on lwip (but not on any specific interface
driver) -- it optionally depends on vfs and esp_eth (need ethernet
header for L2/bridge mode)