esp_efuse_mac_get_default() only stores into the bottom 6 bytes of it's 8-byte argument, so must initialize this arg to zero to avoid trash on the stack.
* Improvements in EspClass
- fixed not working functions for flash chip size, speed and mode
- added function to retrieve chip revision from eFuse
- flashRead / flashWrite supports encrypted flash
* Rename getCpuRevision function to getChipRevision
* Revert: flashRead / flashWrite supports encrypted flash
Reading and writing to encrypted flash has to be aligned to 16-bytes. Also NAND way of writing (i.e. flipping 1s to 0s) will not work with spi_flash_write_encrypted. Note: spi_flash_read_encrypted will always try to decrypt data, even if it wasn't encrypted in the first place.
