staging: rtl8192e: Standardize test for NULL.

The test for NULL of the return variable of functions was changed from
(ret == NULL) to !ret to match the standard.

Coccinelle was used with semantic patch:
@@
expression e;
identifier id, f;
statement S;
@@

f(...) { <+...

id =
\(kmalloc\|devm_kzalloc\|kmalloc_array\|devm_ioremap
\|usb_alloc_urb\|alloc_netdev\|dev_alloc_skb\) (...)

... when any
    when != id = e

+ if (!id)
- if (\(NULL == id\|id == NULL\))
S

...+> }
Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192e/rtl8192e/r8192E_cmdpkt.c

@@ -49,7 +49,7 @@ bool rtl92e_send_cmd_pkt(struct net_device *dev, u32 type, const void *data,
 		else
 			skb = dev_alloc_skb(frag_length + 4);
 
-		if (skb == NULL) {
+		if (!skb) {
 			rt_status = false;
 			goto Failed;
 		}

drivers/staging/rtl8192e/rtllib_rx.c

@@ -130,7 +130,7 @@ rtllib_frag_cache_get(struct rtllib_device *ieee,
 				    ETH_ALEN /* WDS */ +
 				    /* QOS Control */
 				    (RTLLIB_QOS_HAS_SEQ(fc) ? 2 : 0));
-		if (skb == NULL)
+		if (!skb)
 			return NULL;
 
 		entry = &ieee->frag_cache[tid][ieee->frag_next_idx[tid]];
@@ -1430,7 +1430,7 @@ static int rtllib_rx_InfraAdhoc(struct rtllib_device *ieee, struct sk_buff *skb,
 	/* skb: hdr + (possible reassembled) full plaintext payload */
 	payload = skb->data + hdrlen;
 	rxb = kmalloc(sizeof(struct rtllib_rxb), GFP_ATOMIC);
-	if (rxb == NULL)
+	if (!rxb)
 		goto rx_dropped;
 
 	/* to parse amsdu packets */