net/mlx5: enable more shared code on Windows

net/mlx5: enable more shared code on Windows

Use macro HAVE_INFINIBAND_VERBS_H to successfully compile files both
under Linux and Windows (or any non Linux in general). Under Windows
this macro:
1. Hides Verbs references.
2. Exposes required DV structs that are under ifdefs related to rdma
core.

Linux code under definitions such as #ifdef HAVE_IBV_FLOW_DV_SUPPORT is
required unconditionally under Windows however those definitions are
never effective without rdma-core presence. Therefore update the #ifdef
condition to consider HAVE_INFINIBAND_VERBS_H as well (undefined macro
when running without an rdma-core library).

For example:
-#ifdef HAVE_IBV_FLOW_DV_SUPPORT
+#if defined(HAVE_IBV_FLOW_DV_SUPPORT) || !defined(HAVE_INFINIBAND_VERBS_H)

Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>