powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.

commit 10d9161 ("powerpc/64s: Reimplement book3s idle code in C")
reimplemented book3S code to pltform/powernv/idle.c. But when doing so
missed to add the per-thread LDBAR update in the core_woken path of
the power9_idle_stop(). Patch fixes the same.

Fixes: 10d9161 ("powerpc/64s: Reimplement book3s idle code in C")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190702105836.26695-1-maddy@linux.vnet.ibm.com

arch/powerpc/platforms/powernv/idle.c

@@ -762,7 +762,6 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 	mtspr(SPRN_PTCR,	sprs.ptcr);
 	mtspr(SPRN_RPR,		sprs.rpr);
 	mtspr(SPRN_TSCR,	sprs.tscr);
-	mtspr(SPRN_LDBAR,	sprs.ldbar);
 
 	if (pls >= pnv_first_tb_loss_level) {
 		/* TB loss */
@@ -794,6 +793,7 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 	mtspr(SPRN_MMCR0,	sprs.mmcr0);
 	mtspr(SPRN_MMCR1,	sprs.mmcr1);
 	mtspr(SPRN_MMCR2,	sprs.mmcr2);
+	mtspr(SPRN_LDBAR,	sprs.ldbar);
 
 	mtspr(SPRN_SPRG3,	local_paca->sprg_vdso);