clocksource/mips-gic-timer: Print an error if IRQ setup fails

We've checked for errors from setup_irq_percpu since commit f95ac8558b88
("CLOCKSOURCE: mips-gic: Add missing error returns checks") but didn't
print an error message in the failure case. This makes it very easy to
overlook the GIC timer clock event driver not being registered, since
we'll generally just use a different clock event driver if that happens.

Print an error if IRQ setup fails in order to make such problems harder
to miss (ie. not completely silent).

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/20160913165644.627-1-paul.burton@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/clocksource/mips-gic-timer.c

@@ -113,8 +113,11 @@ static int gic_clockevent_init(void)
 		return -ENXIO;
 
 	ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
-	if (ret < 0)
+	if (ret < 0) {
+		pr_err("GIC timer IRQ %d setup failed: %d\n",
+		       gic_timer_irq, ret);
 		return ret;
+	}
 
 	cpuhp_setup_state(CPUHP_AP_MIPS_GIC_TIMER_STARTING,
 			  "AP_MIPS_GIC_TIMER_STARTING", gic_starting_cpu,