serial: cpm_uart: 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/tty/serial/cpm_uart.c

@@ -631,7 +631,7 @@ static int cpm_uart_verify_port(struct uart_port *port,
 
 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_CPM)
 		ret = -EINVAL;
-	if (ser->irq < 0 || ser->irq >= nr_irqs)
+	if (ser->irq < 0 || ser->irq >= irq_get_nr_irqs())
 		ret = -EINVAL;
 	if (ser->baud_base < 9600)
 		ret = -EINVAL;