genirq: Simplify the checks for irq_set_percpu_devid_partition()

Since whether desc is NULL or desc->percpu_enabled is true, it returns
-EINVAL, check them together, and assign desc->percpu_affinity using a
ternary to simplify the code.

Signed-off-by: Jinjie Ruan <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

kernel/irq/irqdesc.c

···
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 
-	if (!desc)
-		return -EINVAL;
-
-	if (desc->percpu_enabled)
+	if (!desc || desc->percpu_enabled)
 		return -EINVAL;
 
 	desc->percpu_enabled = kzalloc(sizeof(*desc->percpu_enabled), GFP_KERNEL);
···
 	if (!desc->percpu_enabled)
 		return -ENOMEM;
 
-	if (affinity)
-		desc->percpu_affinity = affinity;
-	else
-		desc->percpu_affinity = cpu_possible_mask;
+	desc->percpu_affinity = affinity ? : cpu_possible_mask;
 
 	irq_set_percpu_devid_flags(irq);
 	return 0;