V4L/DVB (3439a): media video stradis memory fix

memset clears once set structure, there is actually no need for memset,
because configure function do it for us.  Next, vfree(NULL) is legal, so
avoid useless labels.

Thanks Dave Jones for reporting this.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>