scsi: aha152x: Switch to irq_get_nr_irqs()

Use the irq_get_nr_irqs() function instead of the global variable
'nr_irqs'. Prepare for changing 'nr_irqs' from an exported global
variable into a variable with file scope.

Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

Author: bvanassche

drivers/scsi/aha152x.c

@@ -295,7 +295,7 @@ CMD_INC_RESID(struct scsi_cmnd *cmd, int inc)
 #else
 #define IRQ_MIN 9
 #if defined(__PPC)
-#define IRQ_MAX (nr_irqs-1)
+#define IRQ_MAX (irq_get_nr_irqs()-1)
 #else
 #define IRQ_MAX 12
 #endif