ARM: s3c24xx: bast: avoid irq_desc array usage

Once we move to sparse irqs, the irq_desc[] array is no
longer accessible, so replace the two uses in bast-irq.c.
The first one can use irq_to_desc(), the second one seems
completely unneeded as we already have a pointer to the
correct descriptor.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20200806182059.2431-32-krzk@kernel.orgSigned-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/mach-s3c24xx/bast-irq.c

@@ -62,7 +62,7 @@ bast_pc104_mask(struct irq_data *data)
 static void
 bast_pc104_maskack(struct irq_data *data)
 {
-	struct irq_desc *desc = irq_desc + BAST_IRQ_ISA;
+	struct irq_desc *desc = irq_to_desc(BAST_IRQ_ISA);
 
 	bast_pc104_mask(data);
 	desc->irq_data.chip->irq_ack(&desc->irq_data);
@@ -94,8 +94,6 @@ static void bast_irq_pc104_demux(struct irq_desc *desc)
 
 	if (unlikely(stat == 0)) {
 		/* ack if we get an irq with nothing (ie, startup) */
-
-		desc = irq_desc + BAST_IRQ_ISA;
 		desc->irq_data.chip->irq_ack(&desc->irq_data);
 	} else {
 		/* handle the IRQ */