Staging: rtl8723au: Clean up tests if NULL returned on failure

Some functions like kmalloc/usb_alloc_urb returns Null as their return
value on failure. !x is generally preferred over x==NULL or NULL==x. So
make use of !x if the value returned on failure by these functions is NULL.
Done using coccinelle:

@@
expression e;
statement S;
@@
e = \(kmalloc\|devm_kzalloc\|kmalloc_array
     \|devm_ioremap\|usb_alloc_urb\|alloc_netdev\)(...);
- if(e==NULL)
+ if(!e)
  S
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c

@@ -399,7 +399,7 @@ hal_ReadEFuse_WiFi(struct rtw_adapter *padapter,
 	}
 
 	efuseTbl = kmalloc(EFUSE_MAP_LEN_8723A, GFP_KERNEL);
-	if (efuseTbl == NULL) {
+	if (!efuseTbl) {
 		DBG_8723A("%s: alloc efuseTbl fail!\n", __func__);
 		return;
 	}
@@ -491,7 +491,7 @@ hal_ReadEFuse_BT(struct rtw_adapter *padapter,
 	}
 
 	efuseTbl = kmalloc(EFUSE_BT_MAP_LEN, GFP_KERNEL);
-	if (efuseTbl == NULL) {
+	if (!efuseTbl) {
 		DBG_8723A("%s: efuseTbl malloc fail!\n", __func__);
 		return;
 	}

drivers/staging/rtl8723au/os_dep/xmit_linux.c

@@ -37,7 +37,7 @@ int rtw_os_xmit_resource_alloc23a(struct rtw_adapter *padapter,
 
 	for (i = 0; i < 8; i++) {
 		pxmitbuf->pxmit_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
-		if (pxmitbuf->pxmit_urb[i] == NULL) {
+		if (!pxmitbuf->pxmit_urb[i]) {
 			DBG_8723A("pxmitbuf->pxmit_urb[i]==NULL");
 			return _FAIL;
 		}