net/mlx5: fix errno update in shared context creation

net/mlx5: fix errno update in shared context creation

The mlx5_alloc_shared_dev_ctx() function has a local variable named
"err" which contains the errno value in case of failure.

When functions called by this function are failed, this variable is
updated with their return value (that should be a positive errno value).
However, some functions doesn't update errno value by themselves or
return negative errno value. If one of them fails, the "err" variable
contains negative value what cause to assertion failure.

This patch updates all functions uses by mlx5_alloc_shared_dev_ctx()
function to update rte_errno and take this value instead of "err" value.

Fixes: 5dfa003db53f ("common/mlx5: fix post doorbell barrier")
Fixes: 5d55a494f4e6 ("net/mlx5: split multi-thread flow handling per OS")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>