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>

usb: create common header virtual root hub descriptors

Many USB host controller drivers contain almost identical copies of the
same virtual root hub descriptors. Put these into a common file to avoid
duplication.

Note that there were some very minor differences between the descriptors
in the various files, such as:

- USB 1.0 vs. USB 1.1
- Manufacturer/Device ID
- Max packet size
- String content

I assume these aren't relevant.

Cc: Thomas Lange <thomas@corelatus.se>
Cc: Shinya Kuribayashi <skuribay@pobox.com>
Cc: Gary Jennejohn <garyj@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Eric Millbrandt <emillbrandt@coldhaus.com>
Cc: Pierre Aubert <p.aubert@staubli.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Daniel Hellstrom <daniel@gaisler.com>
Cc: Denis Peter <d.peter@mpl.ch>
Cc: Rodolfo Giometti <giometti@linux.it>
Cc: Zhang Wei <wei.zhang@freescale.com>
Cc: Mateusz Zalega <m.zalega@samsung.com>
Cc: Remy Bohmer <linux@bohmer.net>
Cc: Markus Klotzbuecher <mk@denx.de>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Gary Jennejohn <garyj@denx.de>
Cc: C Nauman <cnauman@diagraph.com>
Cc: David Müller <d.mueller@elsoft.ch>
Cc: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Thomas Abraham <t-abraham@ti.com>
Cc: Tom Rini <trini@ti.com>
Cc: Andrew Murray <amurray@embedded-bits.co.uk>
Cc: Matej Frančeškin <matej.franceskin@comtrade.com>
Cc: Cliff Cai <cliff.cai@analog.com>
Cc: Bryan Wu <cooloney@gmail.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>