net: libwx: fix memory leak on free page

ifconfig ethx up, will set page->refcount larger than 1,
and then ifconfig ethx down, calling __page_frag_cache_drain()
to free pages, it is not compatible with page pool.
So deleting codes which changing page->refcount.

Fixes: 3c47e8ae

 ("net: libwx: Support to receive packets in NAPI")
Signed-off-by: duanqiangwen <duanqiangwen@net-swift.com>
Signed-off-by: David S. Miller <davem@davemloft.net>