mkfs.ext4 requires '-I 256' option to generate filesystems which
support timestamps after 2038

For dunfell the UBI_MTD_NAME is changed from 'spi0.1' to 'UBI'. Now both
naming schemes are supported

Re-programming OTP with the same value doesn't generate an error any more.
OTP locations with value 0 might be unprogrammed or programmed with 0 and
locked. This is not determined and might lead to errors if a value of 0
shall be programmed on a location containing a locked 0. The programming
is required in this case, else all 0 values would never be locked (due to
they wouldn't be being programmed)

- MPTOOL_DEBUG and MPTOOL_SIMULATE is evaluated from environment
- Empty OTP_CFG3_VALUE now skips programming of this OTP location
- Default boot-prios (OTP_CGF3_VALUE) is now empty. Thus it is not programmed
  by default
- New 'flash' command which executes the flash command configured in the config
  file with the key DEFAULT_FLASH_COMMAND. Default is 'flash-bl-fs'

Verification of kontron UID for som and board added

fix issue when writing mac to new device
On writing a mac to a new device mptool complained about an already programmed
mac address. This issue is fixed

use mptool from branch feat_test now as default mptool, rename old mptool
to mptool-classic. Also improve error handling of mptool and create new
sample configuration files for new, more flexible configuration format.

mptool now searches first for mptool_$MEDIUM.config, then for mptool.config
Additionally it searches also for mptool_$MEDIUM.config and mptool.config in $FW_DIR

changed emmc flashing procedure