media: usb: Use kmemdup instead of duplicating its function.

kmemdup has implemented the function that kmalloc() + memcpy().
We prefer to kmemdup rather than code opened implementation.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/dvb-usb-v2/gl861.c

@@ -200,11 +200,10 @@ gl861_i2c_write_ex(struct dvb_usb_device *d, u8 addr, u8 *wbuf, u16 wlen)
 	u8 *buf;
 	int ret;
 
-	buf = kmalloc(wlen, GFP_KERNEL);
+	buf = kmemdup(wbuf, wlen, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	memcpy(buf, wbuf, wlen);
 	ret = usb_control_msg(d->udev, usb_sndctrlpipe(d->udev, 0),
 				 GL861_REQ_I2C_RAW, GL861_WRITE,
 				 addr << (8 + 1), 0x0100, buf, wlen, 2000);