PM / Tracing: build rpm-traces.c only if CONFIG_PM_RUNTIME is set

Do not build kernel/trace/rpm-traces.c if CONFIG_PM_RUNTIME is not
set, which avoids a build failure.

[rjw: Added the changelog and modified the subject slightly.]
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/trace/Makefile

@@ -53,7 +53,9 @@ endif
 obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
 obj-$(CONFIG_TRACEPOINTS) += power-traces.o
+ifeq ($(CONFIG_PM_RUNTIME),y)
 obj-$(CONFIG_TRACEPOINTS) += rpm-traces.o
+endif
 ifeq ($(CONFIG_TRACING),y)
 obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
 endif