The mlx4_en driver allocates the number of objects for the CPU affinity
reverse-map based on the number of rx rings of the device. However,
mlx4_assign_eq() calls irq_cpu_rmap_add() as many times as IRQ's are
assigned to EQ's, which can be as large as mlx4_dev->caps.comp_pool. If
caps.comp_pool is larger than rx_ring_num we will eventually hit the
BUG_ON() in cpu_rmap_add().

Fix this problem by allocating space for the maximum number of CPU
affinity reverse-map objects we might want to add.
Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>