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>