MIPS: Lantiq: Use the real EXIN count

We runtime load the available external interrupts into an array and store
the number inside exin_avail. Some of the code however uses MAX_EIU for
looping over the array which may partially be 0. This is a cosmetic fix as
the existing code works as is. It is just nicer to only loop over the array
elements that were actually populated during probe.
Signed-off-by: John Crispin <john@phrozen.org>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/13602/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/lantiq/irq.c

@@ -125,7 +125,7 @@ static int ltq_eiu_settype(struct irq_data *d, unsigned int type)
 {
 	int i;
 
-	for (i = 0; i < MAX_EIU; i++) {
+	for (i = 0; i < exin_avail; i++) {
 		if (d->hwirq == ltq_eiu_irq[i]) {
 			int val = 0;
 			int edge = 0;
@@ -173,7 +173,7 @@ static unsigned int ltq_startup_eiu_irq(struct irq_data *d)
 	int i;
 
 	ltq_enable_irq(d);
-	for (i = 0; i < MAX_EIU; i++) {
+	for (i = 0; i < exin_avail; i++) {
 		if (d->hwirq == ltq_eiu_irq[i]) {
 			/* by default we are low level triggered */
 			ltq_eiu_settype(d, IRQF_TRIGGER_LOW);
@@ -195,7 +195,7 @@ static void ltq_shutdown_eiu_irq(struct irq_data *d)
 	int i;
 
 	ltq_disable_irq(d);
-	for (i = 0; i < MAX_EIU; i++) {
+	for (i = 0; i < exin_avail; i++) {
 		if (d->hwirq == ltq_eiu_irq[i]) {
 			/* disable */
 			ltq_eiu_w32(ltq_eiu_r32(LTQ_EIU_EXIN_INEN) & ~BIT(i),