ARM: meson: add unique MAC address generation

Add support for generating an unique MAC address using the SoC internal
serial number from the Secure Monitor interface.

The algorithm generates an unicast locally administered 6bytes minus 2bits
address using an crc16 of the serial for the top 16bits with the lower 2 bits
masked to setup the unicast locally administered property and a crc24 for
the lower 24bits.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>