MLX DPDK glue: exclude dependency on OFED libraries

MLX DPDK glue: exclude dependency on OFED libraries

MLX DPDK mlx5_glue.so, compiled under RTE_LIBRTE_MLX5_DLOPEN_DEPS,
provides a run-time check for OFED libraries.
To do so, it links with -libverbs -lmlx5 so that the binding could
occur or fail at runtime (see DPDK 59b91be and VPP 59b91be).
However RPM install fails on systems without OFED installed since
RPM spec has an entry "Requires: libmlx5".
To overcome this, exclude such requirement from the spec.

Same applies to mlx4_glue.so, compiled under RTE_LIBRTE_MLX4_DLOPEN_DEPS

Change-Id: I0ff6efc49581104743cc7e5b1f7cdbc1665ce9ba
Signed-off-by: Igor Mikhailov (imichail) <imichail@cisco.com>