config: gather options for dlopen mlx dependency

config: gather options for dlopen mlx dependency

Rename options CONFIG_RTE_LIBRTE_MLX4_DLOPEN_DEPS and
CONFIG_RTE_LIBRTE_MLX5_DLOPEN_DEPS to a single option
CONFIG_RTE_IBVERBS_LINK_DLOPEN.
Rename meson option enable_driver_mlx_glue to ibverbs_link.

There was no good reason for setting a different link option
for mlx4 and mlx5. Having a single common option makes it
easier to understand and unify make and meson systems.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>