[MIPS] unexport null_perf_irq() and make it static

This patch unexports the null_perf_irq() symbol, and simultaneously
makes this function static.
Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/time.c

@@ -49,13 +49,11 @@ int update_persistent_clock(struct timespec now)
 	return rtc_mips_set_mmss(now.tv_sec);
 }
 
-int null_perf_irq(void)
+static int null_perf_irq(void)
 {
 	return 0;
 }
 
-EXPORT_SYMBOL(null_perf_irq);
-
 int (*perf_irq)(void) = null_perf_irq;
 
 EXPORT_SYMBOL(perf_irq);

arch/mips/oprofile/op_impl.h

@@ -10,7 +10,6 @@
 #ifndef OP_IMPL_H
 #define OP_IMPL_H 1
 
-extern int null_perf_irq(void);
 extern int (*perf_irq)(void);
 
 /* Per-counter configuration as set via oprofilefs.  */

arch/mips/oprofile/op_model_mipsxx.c

@@ -31,6 +31,8 @@
 
 #define M_COUNTER_OVERFLOW		(1UL      << 31)
 
+static int (*save_perf_irq)(void);
+
 #ifdef CONFIG_MIPS_MT_SMP
 static int cpu_has_mipsmt_pertccounters;
 #define WHAT		(M_TC_EN_VPE | \
@@ -369,6 +371,7 @@ static int __init mipsxx_init(void)
 		return -ENODEV;
 	}
 
+	save_perf_irq = perf_irq;
 	perf_irq = mipsxx_perfcount_handler;
 
 	return 0;
@@ -381,7 +384,7 @@ static void mipsxx_exit(void)
 	counters = counters_per_cpu_to_total(counters);
 	on_each_cpu(reset_counters, (void *)counters, 0, 1);
 
-	perf_irq = null_perf_irq;
+	perf_irq = save_perf_irq;
 }
 
 struct op_mips_model op_model_mipsxx_ops = {