powerpc: Avoid debug_smp_processor_id() check in SHARED_PROCESSOR

Use local_paca directly in macro SHARED_PROCESSOR, as all processors
have the same value for the field shared_proc, so we don't need care
racy here.
Reported-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NLi Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/spinlock.h

@@ -96,7 +96,7 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
 
 #if defined(CONFIG_PPC_SPLPAR)
 /* We only yield to the hypervisor if we are in shared processor mode */
-#define SHARED_PROCESSOR (get_lppaca()->shared_proc)
+#define SHARED_PROCESSOR (local_paca->lppaca_ptr->shared_proc)
 extern void __spin_yield(arch_spinlock_t *lock);
 extern void __rw_yield(arch_rwlock_t *lock);
 #else /* SPLPAR */