e1000: possible memory leak in e1000_set_ringparam

Memory allocated for new tx_ring and rx_ring leaks if
e1000_setup_XX_resources() fails.c Also this patch reduces stack usage
(removed tx_new and rx_new) and uses kzalloc instead kmalloc+memset(0)

Signed-off-by: Vasily Averin <vvs@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>