PM: Make sysrq-o be available for CONFIG_PM unset

After commit 1eb208ae, "PM: Make
CONFIG_PM depend on (CONFIG_PM_SLEEP || CONFIG_PM_RUNTIME)", the
files under kernel/power are not built unless CONFIG_PM_SLEEP or
CONFIG_PM_RUNTIME is set.  In particular, this causes
kernel/power/poweroff.c to be omitted, even though it should be
compiled, because CONFIG_MAGIC_SYSRQ is set.

Fix the problem by causing kernel/power/Makefile to be processed
for CONFIG_PM unset too.
Reported-and-tested-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/Makefile

@@ -23,6 +23,7 @@ CFLAGS_REMOVE_irq_work.o = -pg
 endif
 
 obj-y += sched/
+obj-y += power/
 
 obj-$(CONFIG_FREEZER) += freezer.o
 obj-$(CONFIG_PROFILING) += profile.o
@@ -52,8 +53,6 @@ obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
 obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
-obj-$(CONFIG_PM) += power/
-obj-$(CONFIG_FREEZER) += power/
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o