[PATCH] powerpc/powernv/idle: Put pnv_cpu_offline behind HOTPLUG_CPU

[Joel Stanley <joel@jms.id.au>]

In commit 900612315788 ("powerpc/powernv/smp: Add busy-wait loop as fall back
for CPU-Hotplug") the idle code uses generic_check_cpu_restart(), but that
function is not available when CONFIG_HOTPLUG_CPU is disabled.

arch/powerpc/platforms/powernv/idle.c: In function ‘pnv_cpu_offline’:
arch/powerpc/platforms/powernv/idle.c:286:11: error: implicit declaration of
function ‘generic_check_cpu_restart’ [-Werror=implicit-function-declaration]
   while (!generic_check_cpu_restart(cpu)) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~

The callers of pnv_cpu_offline are behind CONFIG_HOTPLUG_CPU, so fix the build
error by putting this code behind the same gard.

Fixes: 900612315788 ("powerpc/powernv/smp: Add busy-wait loop as fall back for CPU-Hotplug").
Cc: <stable@vger.kernel.org> # 4.12
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 arch/powerpc/platforms/powernv/idle.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 445f30a2c5ef..b15d108db216 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -261,6 +261,8 @@ static u64 pnv_deepest_stop_psscr_val;
 static u64 pnv_deepest_stop_psscr_mask;
 static bool deepest_stop_found;
 
+#ifdef CONFIG_HOTPLUG_CPU
+
 /*
  * pnv_cpu_offline: A function that puts the CPU into the deepest
  * available platform idle state on a CPU-Offline.
@@ -294,6 +296,8 @@ unsigned long pnv_cpu_offline(unsigned int cpu)
 	return srr1;
 }
 
+#endif /* CONFIG_HOTPLUG_CPU */
+
 /*
  * Power ISA 3.0 idle initialization.
  *
-- 
2.13.2