staging: r8188eu: os_dep: use kmemdup instead of kzalloc and memcpy

Fixes coccicheck warning:WARNING opportunity for kmemdup in ioctl_linux.c
Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Saurav Girepunje <saurav.girepunje@gmail.com>
Link: https://lore.kernel.org/r/YTJhwQstKPUYRwN+@userSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/os_dep/ioctl_linux.c

@@ -585,14 +585,12 @@ static int rtw_set_wpa_ie(struct adapter *padapter, char *pie, unsigned short ie
 	}
 
 	if (ielen) {
-		buf = kzalloc(ielen, GFP_KERNEL);
+		buf = kmemdup(pie, ielen, GFP_KERNEL);
 		if (!buf) {
 			ret =  -ENOMEM;
 			goto exit;
 		}
 
-		memcpy(buf, pie, ielen);
-
 		/* dump */
 		{
 			int i;