net/mlx5: Remove references to local mlx5_core functions

As a preparation to move SRQ functionality to RDMA, drop all references
to mlx5_core logic and make SRQ be dependent on shared code only.

Most of the time, we are interested to know if events are working/not
working and it is possible with previous commit ("net/mlx5: Debug print
for forwarded async events").

Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>