net/mlx4: fix Rx resource leak in case of error

net/mlx4: fix Rx resource leak in case of error

When creation of a flow rule fails during dev_start(), the usage count of
the common RSS context is not decremented, which triggers an assertion
failure in debug mode during dev_close().

This is addressed by tracking the initialization status of the common RSS
context in order to add missing cleanup code.

A similar issue exists in mlx4_rxq_attach(), where usage count is
incremented on a Rx queue but not released in case of error. This may lead
to the above issue since RSS contexts created by flow rules attach
themselves to Rx queues, incrementing their usage count.

Fixes: 5697a4142107 ("net/mlx4: relax Rx queue configuration order")
Cc: stable@dpdk.org
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>