feat(esp_modem_usb_dte): add esp32p4 support & add cat.4 ec20 modem

[leeebo]

As esp32p4 has been supported in usb_host_cdc_acm, it should be the right time for us to support higher throughput Cat.4 Cellular module (DL 150 Mbps, UL 50 Mbps).

• Support esp32p4 in esp_modem_usb_dte
• Add Cat.4 module EC20
• Add support in esp_modem example feat(esp_modem): example add esp32p4 usb support (IDFGH-12673) esp-protocols#556
  - [ ] Speed iperf test

[tore-espressif]

@leeebo Thank you for the update!

There is one outstanding issue for some USB modems on P4. Sometimes the esp_modem tries to append received data to USB data buffer, which causes error with unaligned cache sync.

We can merge it now and I can fix it later, what do you think?

[david-cermak]

There is one outstanding issue for some USB modems on P4. Sometimes the esp_modem tries to append received data to USB data buffer, which causes error with unaligned cache sync.

@leeebo @tore-espressif Do you think it's happening only on P4? Probably not the cache sync issue, but maybe those "appended fragments" getting lost?
I hear there're still some stability issues when using USB with esp_modem (compared to UART), the latest is here espressif/esp-protocols#589

[tore-espressif]

This particular issue is only relevant for P4.

I can check the issue you linked, but no sooner then end of this month