staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set_scan

staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set_scan

Function _rtl92e_wx_set_scan calls memcpy without checking the length.
A user could control that length and trigger a buffer overflow.
Fix by checking the length is within the maximum allowed size.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lee Gibson <leegib@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210226145157.424065-1-leegib@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>