kernel.bbclass/linux-wrs: move definition of perf package to kernel class

By defining the perf package in the shared kernel class bitbake will be able to
find the package provider even when the preferred kernel doesn't build perf,
preventing dependency resolution failures.

Signed-off-by: Joshua Lock <josh@linux.intel.com>

meta/classes/kernel.bbclass

@@ -501,3 +501,8 @@ do_deploy() {
 do_deploy[dirs] = "${DEPLOYDIR} ${B}"
 
 addtask deploy before do_package after do_install
+
+# perf must be enabled in individual kernel recipes
+PACKAGES =+ "perf"
+FILES_perf = "${bindir}/* \
+              ${libexecdir}"