refscale: Allow CPU hotplug to be enabled

It is no longer possible to disable CPU hotplug in many configurations,
which means that the CONFIG_HOTPLUG_CPU=n lines in refscale's Kconfig
options are just a source of useless diagnostics.  In addition, refscale
doesn't do CPU-hotplug operations in any case.  This commit therefore
changes these lines to read CONFIG_HOTPLUG_CPU=y.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT

@@ -7,7 +7,7 @@ CONFIG_HZ_PERIODIC=n
 CONFIG_NO_HZ_IDLE=y
 CONFIG_NO_HZ_FULL=n
 CONFIG_RCU_FAST_NO_HZ=n
-CONFIG_HOTPLUG_CPU=n
+CONFIG_HOTPLUG_CPU=y
 CONFIG_SUSPEND=n
 CONFIG_HIBERNATION=n
 CONFIG_RCU_NOCB_CPU=n

tools/testing/selftests/rcutorture/configs/refscale/PREEMPT

@@ -7,7 +7,7 @@ CONFIG_HZ_PERIODIC=n
 CONFIG_NO_HZ_IDLE=y
 CONFIG_NO_HZ_FULL=n
 CONFIG_RCU_FAST_NO_HZ=n
-CONFIG_HOTPLUG_CPU=n
+CONFIG_HOTPLUG_CPU=y
 CONFIG_SUSPEND=n
 CONFIG_HIBERNATION=n
 CONFIG_RCU_NOCB_CPU=n