net/mlx5: Remove unused msix related exported APIs

net/mlx5: Remove unused msix related exported APIs

MSIX irq allocation and free APIs are no longer
in use. Hence, remove the dead code.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://lore.kernel.org/r/20240512124306.740898-4-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>