gve: DQO: Remove incorrect prefetch

The prefetch is incorrectly using the dma address instead of the virtual
address.

It's supposed to be:
prefetch((char *)buf_state->page_info.page_address +
	 buf_state->page_info.page_offset)

However, after correcting this mistake, there is no evidence of
performance improvement.

Fixes: 9b8dd5e5

 ("gve: DQO: Add RX path")
Signed-off-by: Bailey Forrest <bcf@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>