Commit 68823df358 ("acpi: Re-license ACPI builder files from GPLv2 to
LGPLv2.1") added references to a "special exception on linking described
in file LICENSE", without actually adding such a file. Quite likely
COPYING was meant instead, yet then its text matches LICENSES/LGPL-2.1
except for some explanatory text (clarifying the "only" aspect) at the
top (and formatting). Hence replace the text in all the files with SPDX
references to LGPL-2.1.
Note that dsdt_acpi_info.asl had no license text. An SPDX tag is being
added there nevertheless.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>