staging: ks7010: fix checkpatch memset warning

Checkpatch emits WARNING: single byte memset is suspicious. Swapped
2nd/3rd argument? Call site in question is correct but is an unusual
use of memset() to zero a single byte. The same can be achieved by
assigning 0 directly to the memory location.

Dereference pointer and assign 0 to that memory location. Use '\0' to
make explicit that it is a char pointer.
Signed-off-by: NTobin C. Harding <me@tobin.cc>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/ks7010/ks_wlan_net.c

@@ -2431,7 +2431,7 @@ static int ks_wlan_data_read(struct net_device *dev,
 			return 0;
 		}
 		read_length = 0;
-		memset(extra, 0, 1);
+		*extra = '\0';
 		dwrq->length = 0;
 		return 0;
 	}