SPDX: Convert all of our single license tags to Linux Kernel style

When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from. So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry. Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents. There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>

cmd: eeprom: add support for layout aware commands

Introduce the (optional) eeprom print and eeprom update commands.

These commands are eeprom layout aware:
* The eeprom print command prints the contents of the eeprom in a human
readable way (eeprom layout fields, and data formatted to be fit for human
consumption).
* The eeprom update command allows user to update eeprom fields by specifying
the field name, and providing the new data in a human readable format (same
format as displayed by the eeprom print command).
* Both commands can either auto detect the layout, or be told which layout to
use.

New CONFIG options:
CONFIG_CMD_EEPROM_LAYOUT - enables commands.
CONFIG_EEPROM_LAYOUT_HELP_STRING - tells user what layout names are supported

Feature API:
__weak int parse_layout_version(char *str)
- override to provide your own layout name parsing
__weak void __eeprom_layout_assign(struct eeprom_layout *layout, int layout_version);
- override to setup the layout metadata based on the version
__weak int eeprom_layout_detect(unsigned char *data)
- override to provide your own algorithm for detecting layout version
eeprom_field.c
- contains various printing and updating functions for common types of
eeprom fields. Can be used for defining custom layouts.

Cc: Heiko Schocher <hs@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Tom Rini <trini@konsulko.com>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>