staging:rtl8192u: Correct comparison with NULL - Style

Correct code to remote comparison with NULL, this clears the resulting
checkpatch issue.

This is a coding style change which should not impact runtime code
execution.
Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/ieee80211/ieee80211_module.c

@@ -280,7 +280,7 @@ int __init ieee80211_debug_init(void)
 	ieee80211_debug_level = debug;
 
 	ieee80211_proc = proc_mkdir(DRV_NAME, init_net.proc_net);
-	if (ieee80211_proc == NULL) {
+	if (!ieee80211_proc) {
 		IEEE80211_ERROR("Unable to create " DRV_NAME
 				" proc directory\n");
 		return -EIO;