drivers: hwinfo: stm32: Add support for reading EUI64 on STM32W*

The STM32WB, STM32WB and STM32WBA families devices include a EUI64 ID
(called "IEEE 64-bit unique device ID register" in the reference manual
that is distinct from the standard device ID. Add support for reading
it, noting that it is stored in little endian format in the registers.

On other families the weak implementation takes over and returns
-ENOSYS.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>