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/automake/automake.inc

@@ -1,7 +1,7 @@
 SUMMARY = "A GNU tool for automatically generating Makefiles"
 DESCRIPTION = "Automake is a tool for automatically generating `Makefile.in' files compliant with the GNU Coding \
 Standards. Automake requires the use of Autoconf."
-LICENSE = "GPLv2"
+LICENSE = "GPL-2.0-only"
 HOMEPAGE = "http://www.gnu.org/software/automake/"
 SECTION = "devel"
 

meta/recipes-devtools/automake/automake_1.16.5.bb

@@ -1,5 +1,5 @@
 require automake.inc
-LICENSE = "GPLv2"
+LICENSE = "GPL-2.0-only"
 LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
 DEPENDS:class-native = "autoconf-native"