net/ena: cleanup if refilling of Rx descriptors fails

net/ena: cleanup if refilling of Rx descriptors fails

If wrong number of descriptors for refilling was passed to the Rx
repopulate function, there was memory leak which caused memory pool to
run out of resources in longer go.

In case of fail when refilling Rx descriptors, all additional mbufs
have to be released.

Fixes: 1173fca25af9 ("ena: add polling-mode driver")
Cc: stable@dpdk.org
Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Jakub Palider <jpalider@gmail.com>
Acked-by: Jan Medala <jan.medala@outlook.com>