s2io: Fix warnings due to -Wunused-but-set-variable.

Most of these are cases where we are trying to read back a register
after a write to ensure completion.

Simply pre-fixing the readl() or readq() with "(void)" is sufficient
because these are volatile operations and the compiler cannot eliminate
them just because no real assignment takes place.

The case of free_rxd_blk()'s assignments to "struct buffAdd *ba" is a
real spurious assignment as this variable is completely otherwise
unused.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Jon Mason <jdmason@kudzu.us>

drivers/net/s2io.c

@@ -2244,13 +2244,12 @@ static int verify_xena_quiescence(struct s2io_nic *sp)
 static void fix_mac_address(struct s2io_nic *sp)
 {
 	struct XENA_dev_config __iomem *bar0 = sp->bar0;
-	u64 val64;
 	int i = 0;
 
 	while (fix_mac[i] != END_SIGN) {
 		writeq(fix_mac[i++], &bar0->gpio_control);
 		udelay(10);
-		val64 = readq(&bar0->gpio_control);
+		(void) readq(&bar0->gpio_control);
 	}
 }
 
@@ -2727,7 +2726,6 @@ static void free_rxd_blk(struct s2io_nic *sp, int ring_no, int blk)
 	int j;
 	struct sk_buff *skb;
 	struct RxD_t *rxdp;
-	struct buffAdd *ba;
 	struct RxD1 *rxdp1;
 	struct RxD3 *rxdp3;
 	struct mac_info *mac_control = &sp->mac_control;
@@ -2751,7 +2749,6 @@ static void free_rxd_blk(struct s2io_nic *sp, int ring_no, int blk)
 			memset(rxdp, 0, sizeof(struct RxD1));
 		} else if (sp->rxd_mode == RXD_MODE_3B) {
 			rxdp3 = (struct RxD3 *)rxdp;
-			ba = &mac_control->rings[ring_no].ba[blk][j];
 			pci_unmap_single(sp->pdev,
 					 (dma_addr_t)rxdp3->Buffer0_ptr,
 					 BUF0_LEN,

drivers/net/s2io.h

@@ -1002,18 +1002,16 @@ static inline void writeq(u64 val, void __iomem *addr)
 #define LF	2
 static inline void SPECIAL_REG_WRITE(u64 val, void __iomem *addr, int order)
 {
-	u32 ret;
-
 	if (order == LF) {
 		writel((u32) (val), addr);
-		ret = readl(addr);
+		(void) readl(addr);
 		writel((u32) (val >> 32), (addr + 4));
-		ret = readl(addr + 4);
+		(void) readl(addr + 4);
 	} else {
 		writel((u32) (val >> 32), (addr + 4));
-		ret = readl(addr + 4);
+		(void) readl(addr + 4);
 		writel((u32) (val), addr);
-		ret = readl(addr);
+		(void) readl(addr);
 	}
 }