RDMA/mlx5: Fix CC counters query for MPV

RDMA/mlx5: Fix CC counters query for MPV

In case, CC counters are querying for the second port use the correct
core device for the query instead of always using the master core device.

Fixes: aac4492ef23a ("IB/mlx5: Update counter implementation for dual port RoCE")
Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://patch.msgid.link/9cace74dcf106116118bebfa9146d40d4166c6b0.1750064969.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>