layer.conf: avoid unnecessary early expansion with :=

bitbake handles immediate expansions of LAYERDIR for us automatically.

(From OE-Core rev: 643ac87145eba5dc105377041bc3deb163b62926)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/layer.conf

@@ -4,7 +4,7 @@ BBPATH .= ":${LAYERDIR}"
 BBFILES += "${LAYERDIR}/recipes-*/*/*.bb"
 
 BBFILE_COLLECTIONS += "core"
-BBFILE_PATTERN_core := "^${LAYERDIR}/"
+BBFILE_PATTERN_core = "^${LAYERDIR}/"
 BBFILE_PRIORITY_core = "5"
 
 # This should only be incremented on significant changes that will
@@ -12,10 +12,10 @@ BBFILE_PRIORITY_core = "5"
 LAYERVERSION_core = "1"
 
 # Set a variable to get to the top of the metadata location
-COREBASE := '${@os.path.normpath("${LAYERDIR}/../")}'
+COREBASE = '${@os.path.normpath("${LAYERDIR}/../")}'
 
 # Set path to qemu image tests included in this layer
-QEMUIMAGETESTS := "${COREBASE}/scripts/qemuimage-tests"
+QEMUIMAGETESTS = "${COREBASE}/scripts/qemuimage-tests"
 
 SIGGEN_EXCLUDERECIPES_ABISAFE += " \
   sysvinit-inittab \