sh: mach-highlander: Handle virq offset in cascaded IRL demux

Take into account the virq offset when translating cascaded IRL
interrupts.

Fixes: a8ac2961 ("sh: Avoid using IRQ0 on SH3 and SH4")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/4fcb0d08a2b372431c41e04312742dc9e41e1be4.1688908186.git.geert+renesas@glider.beSigned-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

arch/sh/boards/mach-highlander/setup.c

@@ -389,10 +389,10 @@ static unsigned char irl2irq[HL_NR_IRL];
 
 static int highlander_irq_demux(int irq)
 {
-	if (irq >= HL_NR_IRL || irq < 0 || !irl2irq[irq])
+	if (irq >= HL_NR_IRL + 16 || irq < 16 || !irl2irq[irq - 16])
 		return irq;
 
-	return irl2irq[irq];
+	return irl2irq[irq - 16];
 }
 
 static void __init highlander_init_irq(void)