gve: fix unused variable/label warnings

On unusual page sizes, we get harmless warnings:

drivers/net/ethernet/google/gve/gve_rx.c:283:6: error: unused variable 'pagecount' [-Werror,-Wunused-variable]
drivers/net/ethernet/google/gve/gve_rx.c:336:1: error: unused label 'have_skb' [-Werror,-Wunused-label]

Change the preprocessor #if to regular if() to avoid this.

Fixes: f5cedc84 ("gve: Add transmit and receive support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/google/gve/gve_rx.c

@@ -297,7 +297,7 @@ static bool gve_rx(struct gve_rx_ring *rx, struct gve_rx_desc *rx_desc,
 	 * it so that we can return it to the device.
 	 */
 
-#if PAGE_SIZE == 4096
+	if (PAGE_SIZE == 4096) {
 		if (len <= priv->rx_copybreak) {
 			/* Just copy small packets */
 			skb = gve_rx_copy(dev, napi, page_info, len);
@@ -329,9 +329,9 @@ static bool gve_rx(struct gve_rx_ring *rx, struct gve_rx_desc *rx_desc,
 			WARN(pagecount < 1, "Pagecount should never be < 1");
 			return false;
 		}
-#else
+	} else {
 		skb = gve_rx_copy(dev, napi, page_info, len);
-#endif
+	}
 
 have_skb:
 	/* We didn't manage to allocate an skb but we haven't had any