Modify license to include dual licensing as GPL-2.0-only OR MIT
license for device trees belonging to PHYTEC Messtechnik GmbH and
PHYTEC America, LLC platforms. This allows for Linux kernel device
tree to be used in other Operating System ecosystems such as Zephyr or
FreeBSD.

While at this, update the GPL-2.0 to be GPL-2.0-only to be in sync
with latest SPDX conventions (GPL-2.0 is deprecated).

While at this, update the copyright year to sync with current year
to indicate license change.

Cc: Garrett Giordano <ggiordano@phytec.com>
Cc: Wadim Egorov <w.egorov@phytec.de>
Acked-by: Garrett Giordano <ggiordano@phytec.com>
Acked-by: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240122145539.194512-15-nm@ti.comSigned-off-by: Vignesh Raghavendra <vigneshr@ti.com>