meta/meta-selftest/meta-skeleton: Update LICENSE variable to use SPDX license identifiers

An automated conversion using scripts/contrib/convert-spdx-licenses.py to
convert to use the standard SPDX license identifiers. Two recipes in meta-selftest
were not converted as they're that way specifically for testing. A change in
linux-firmware was also skipped and may need a more manual tweak.

(From OE-Core rev: ceda3238cdbf1beb216ae9ddb242470d5dfc25e0)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/qemu/nativesdk-qemu-helper_1.0.bb

@@ -1,5 +1,5 @@
 SUMMARY = "Qemu helper scripts"
-LICENSE = "GPLv2"
+LICENSE = "GPL-2.0-only"
 RDEPENDS:${PN} = "nativesdk-qemu \
                   nativesdk-python3-shell nativesdk-python3-fcntl nativesdk-python3-logging \
                 "

meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb

@@ -1,5 +1,5 @@
 SUMMARY = "Helper utilities needed by the runqemu script"
-LICENSE = "GPLv2"
+LICENSE = "GPL-2.0-only"
 RDEPENDS:${PN} = "qemu-system-native"
 PR = "r1"
 

meta/recipes-devtools/qemu/qemu.inc

@@ -4,7 +4,7 @@ machine's processor through dynamic binary translation and provides a set \
 of different hardware and device models for the machine, enabling it to run \
 a variety of guest operating systems"
 HOMEPAGE = "http://qemu.org"
-LICENSE = "GPLv2 & LGPLv2.1"
+LICENSE = "GPL-2.0-only & LGPL-2.1-only"
 
 RDEPENDS:${PN}-ptest = "bash"