staging: rtl8192u: use memdup_user to simplify code

Use memdup_user rather than duplicating its implementation. Fix the
following coccinelle warnings:

drivers/staging/rtl8192u/r8192U_core.c:3792:7-14: WARNING opportunity for memdup_user
drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c:3153:9-16: WARNING opportunity for memdup_user
Signed-off-by: Teodora Baluta <teobaluta@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c

@@ -3150,14 +3150,9 @@ int ieee80211_wpa_supplicant_ioctl(struct ieee80211_device *ieee, struct iw_poin
 		goto out;
 	}
 
-	param = kmalloc(p->length, GFP_KERNEL);
-	if (param == NULL){
-		ret = -ENOMEM;
-		goto out;
-	}
-	if (copy_from_user(param, p->pointer, p->length)) {
-		kfree(param);
-		ret = -EFAULT;
+	param = memdup_user(p->pointer, p->length);
+	if (IS_ERR(param)) {
+		ret = PTR_ERR(param);
 		goto out;
 	}
 

drivers/staging/rtl8192u/r8192U_core.c

@@ -3789,14 +3789,9 @@ int rtl8192_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		goto out;
 	}
 
-	ipw = kmalloc(p->length, GFP_KERNEL);
-	if (ipw == NULL) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	if (copy_from_user(ipw, p->pointer, p->length)) {
-		kfree(ipw);
-		ret = -EFAULT;
+	ipw = memdup_user(p->pointer, p->length);
+	if (IS_ERR(ipw)) {
+		ret = PTR_ERR(ipw);
 		goto out;
 	}