[MIPS] time: Fix negated condition in cevt-r4k driver.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index bab935a..076f52b 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -276,7 +276,7 @@
 
 	clockevents_register_device(cd);
 
-	if (!cp0_timer_irq_installed)
+	if (cp0_timer_irq_installed)
 		return;
 
 	cp0_timer_irq_installed = 1;