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>

Add GPL-2.0+ SPDX-License-Identifier to source files

Signed-off-by: Wolfgang Denk <wd@denx.de>
[trini: Fixup common/cmd_io.c]
Signed-off-by: Tom Rini <trini@ti.com>

common: Add .u_boot_list into all linker files

Add section for the linker-generated lists into all possible linker
files, so that everyone can easily use these lists. This is mostly
a mechanical adjustment.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>

Fix build problems caused by "_end" -> "__bss_end__" rename

Commit 44c6e65 "rename _end to __bss_end__ broke building of a large
number of systems (at least all PowerPC?):

libstubs.o: In function `app_startup':
examples/standalone/stubs.c:197: undefined reference to `__bss_end__'

The rename should not be done for the files in the
examples/standalone/ directory, as these are not using the code from
start.S, but do their own BSS clearing, and either use their own
linker scripts or the ones provided by the compilers.

Signed-off-by: Po-Yu Chuang <ratbert@faraday-tech.com>
Signed-off-by: Wolfgang Denk <wd@denx.de>

rename _end to __bss_end__

Currently, _end is used for end of BSS section. We want _end to mean
end of u-boot image, so we rename _end to __bss_end__ first.

Signed-off-by: Po-Yu Chuang <ratbert@faraday-tech.com>

Move examples/ to examples/standalone

The current files in examples are all standalone application examples,
so put them in their own subdirectory for organizational purposes

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>