net/mlx5: HWS, expose polling function in header file

In preparation for complex matcher, expose the function that is
polling queue for completion (mlx5hws_bwc_queue_poll) in header
file, so that it will be used by complex matcher code.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Vlad Dogaru <vdogaru@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1746992290-568936-4-git-send-email-tariqt@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>