net/mlx5: Fix build break when CONFIG_SMP=n

Avoid using the kernel's irq_descriptor and return IRQ vector affinity
directly from the driver.

This fixes the following build break when CONFIG_SMP=n

include/linux/mlx5/driver.h: In function ‘mlx5_get_vector_affinity_hint’:
include/linux/mlx5/driver.h:1299:13: error:
        ‘struct irq_desc’ has no member named ‘affinity_hint’

Fixes: 6082d9c ("net/mlx5: Fix mlx5_get_vector_affinity function")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
CC: Randy Dunlap <rdunlap@infradead.org>
CC: Guenter Roeck <linux@roeck-us.net>
CC: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Israel Rukshin <israelr@mellanox.com>
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Saeed Mahameed

include/linux/mlx5/driver.h

@@ -1286,17 +1286,7 @@ enum {
 static inline const struct cpumask *
 mlx5_get_vector_affinity_hint(struct mlx5_core_dev *dev, int vector)
 {
-	struct irq_desc *desc;
-	unsigned int irq;
-	int eqn;
-	int err;
-
-	err = mlx5_vector2eqn(dev, vector, &eqn, &irq);
-	if (err)
-		return NULL;
-
-	desc = irq_to_desc(irq);
-	return desc->affinity_hint;
+	return dev->priv.irq_info[vector].mask;
 }
 
 #endif /* MLX5_DRIVER_H */