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>

Revert "drivers/ddr/fsl: Dual-license DDR driver"

Upon further review, not all code authors are in favour of this change.
This reverts commit ee3556bcafbb05e59aabdc31368984e76acaabc4.

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

drivers/ddr/fsl: Dual-license DDR driver

To make this driver easier to be reused, dual-license DDR driver.

Signed-off-by: York Sun <york.sun@nxp.com>
CC: Simon Glass <sjg@chromium.org>
CC: Tom Rini <trini@konsulko.com>
CC: Heinrich Schuchardt <xypron.glpk@gmx.de>
CC: Thomas Schaefer <thomas.schaefer@kontron.com>
CC: Masahiro Yamada <yamada.masahiro@socionext.com>
CC: Robert P. J. Day <rpjday@crashcourse.ca>
CC: Alexander Merkle <alexander.merkle@lauterbach.com>
CC: Joakim Tjernlund <joakim.tjernlund@transmode.se>
CC: Curt Brune <curt@cumulusnetworks.com>
CC: Valentin Longchamp <valentin.longchamp@keymile.com>
CC: Wolfgang Denk <wd@denx.de>
CC: Anatolij Gustschin <agust@denx.de>
CC: Ira W. Snyder <iws@ovro.caltech.edu>
CC: Marek Vasut <marek.vasut@gmail.com>
CC: Kyle Moffett <Kyle.D.Moffett@boeing.com>
CC: Sebastien Carlier <sebastien.carlier@gmail.com>
CC: Stefan Roese <sr@denx.de>
CC: Peter Tyser <ptyser@xes-inc.com>
CC: Paul Gortmaker <paul.gortmaker@windriver.com>
CC: Peter Tyser <ptyser@xes-inc.com>
CC: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

driver/ddr/fsl: Add DDR4 support to Freescale DDR driver

Mostly reusing DDR3 driver, this patch adds DDR4 SPD handling, register
calculation and programming.

Signed-off-by: York Sun <yorksun@freescale.com>