staging: vt6656: sparse fixes: iwctl_giwgenie use memcpy.

extra is in kernel space use memcpy.

sparse warning
iwctl.c:1595:42: warning: incorrect type in argument 1 (different address spaces)
iwctl.c:1595:42:    expected void [noderef] <asn:1>*to
iwctl.c:1595:42:    got char *extra

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>