common/sfc_efx/base: introduce states for UDP tunnel entries

common/sfc_efx/base: introduce states for UDP tunnel entries

UDP tunnel reconfigure operation takes UDP tunnel table, which contains
entries that need to be applied to HW. This approach does not retain
information about what entries were removed or added, which is required
for Riverhead.

Add states to the table entries to indicate add or remove operations.
On tunnel reconfiguration added and removed entries become busy to
indicate that the entries are currently configured and to prevent add or
remove operations from other threads. After tunnel reconfiguration is
complete, the states are reset - added entries become applied and
removed entries are purged from the table.

Signed-off-by: Igor Romanov <igor.romanov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>