nfp: flower: release metadata on offload failure

nfp: flower: release metadata on offload failure

Calling nfp_compile_flow_metadata both assigns a stats context and
increments a ref counter on (or allocates) a mask id table entry. These
are released by the nfp_modify_flow_metadata call on flow deletion,
however, if a flow add fails after metadata is set then the flow entry
will be deleted but the metadata assignments leaked.

Add an error path to the flow add offload function to ensure allocated
metadata is released in the event of an offload fail.

Fixes: 2095a1a884d4 ("nfp: add control message passing capabilities to flower offloads")
Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>