net/mlx5: IRQ, Fix null string in debug print

net/mlx5: IRQ, Fix null string in debug print

irq_pool_alloc() debug print can print a null string.
Fix it by providing a default string to print.

Fixes: 71e084e26414 ("net/mlx5: Allocating a pool of MSI-X vectors for SFs")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501141055.SwfIphN0-lkp@intel.com/
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20250225072608.526866-4-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>