drivers: hwinfo: Add support for ESP32

ESP32 can sport up to 4 network interfaces: two 802.11 (station and
ap), ethernet, and bluetooth.  All of them derive from the same RDATA
register in efuse block 0.  However, in most cases, the last (sixth)
octet will change like so:

  - 802.11 station:  mac[5] += 0
  - 802.11 ap:       mac[5] += 1
  - bluetooth:       mac[5] += 2
  - ethernet:        mac[5] += 3

Read "Number of universally admnistered MAC address" section in esp-idf
documentation[1] for more information.

[1] https://docs.espressif.com/projects/esp-idf/en/latest/

Signed-off-by: Leandro Pereira <leandro@hardinfo.org>