staging: rtl8192u: Replace explicit NULL comparison

Replace explicit NULL comparison with ! operator to
simplify code.

Found with Coccinelle script:
@@
expression ptr;
position p;
statement s0, s1;
@@

ptr@p =
\(kmalloc\|devm_kzalloc\|kmalloc_array\|devm_ioremap\|usb_alloc_urb\|
alloc_netdev\|dev_alloc_skb\)(...)
... when != ptr

if (
(
+ !
ptr
- == NULL
)
) s0 else s1
Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/ieee80211/rtl819x_BAProc.c

@@ -117,7 +117,7 @@ static struct sk_buff *ieee80211_ADDBA(struct ieee80211_device *ieee, u8 *Dst, P
 		return NULL;
 	}
 	skb = dev_alloc_skb(len + sizeof( struct rtl_80211_hdr_3addr)); //need to add something others? FIXME
-	if (skb == NULL) {
+	if (!skb) {
 		IEEE80211_DEBUG(IEEE80211_DL_ERR, "can't alloc skb for ADDBA_REQ\n");
 		return NULL;
 	}
@@ -202,7 +202,7 @@ static struct sk_buff *ieee80211_DELBA(
 	DelbaParamSet.field.TID	= pBA->BaParamSet.field.TID;
 
 	skb = dev_alloc_skb(len + sizeof( struct rtl_80211_hdr_3addr)); //need to add something others? FIXME
-	if (skb == NULL) {
+	if (!skb) {
 		IEEE80211_DEBUG(IEEE80211_DL_ERR, "can't alloc skb for ADDBA_REQ\n");
 		return NULL;
 	}