powerpc/kprobes: Have optimized_callback() use preempt_enable()

Similar to x86 commit 2e62024c ("kprobes/x86: Use preempt_enable()
in optimized_callback()"), change powerpc optprobes to use
preempt_enable() rather than preempt_enable_no_resched() since powerpc
also removed irq disabling for optprobes in commit f72180cc
("powerpc/kprobes: Do not disable interrupts for optprobes and
kprobes_on_ftrace").
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@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/1885bab182626c33d9bf6421f430abf924c521a5.1666262278.git.naveen.n.rao@linux.vnet.ibm.com

arch/powerpc/kernel/optprobes.c

@@ -112,7 +112,7 @@ static void optimized_callback(struct optimized_kprobe *op,
 		__this_cpu_write(current_kprobe, NULL);
 	}
 
-	preempt_enable_no_resched();
+	preempt_enable();
 }
 NOKPROBE_SYMBOL(optimized_callback);