ibmvnic: Reset tx/rx pools on driver reset

When resetting the ibmvnic driver there is not a need to release
and re-allocate the resources for the tx and rx pools. These
resources can just be reset to avoid the re-allocations.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>