tg3: Fix a memory leak on 5717+ devices

The rx resources for MSI-X interrupt vector 0 were not being freed
correctly.  This happens because the teardown loop continue's to the
next loop iteration if it detects the tx ring for that vector is not
setup, thus bypassing the rx teardown code.  This patch moves the
call to tg3_rx_prodring_free() earlier in the loop.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>