[media] v4l: make sure drivers supply a zeroed struct v4l2_subdev

Some v4l drivers currently don't initialize their struct v4l2_subdev
with zeros, and this is a problem since some of the v4l2 code expects
this. One example is the addition of internal_ops in commit 45f6f84,
after that we are at risk of random oopses with these drivers when code
in v4l2_device_register_subdev tries to dereference sd->internal_ops->*,
as can be shown by the report at http://bugs.launchpad.net/bugs/745213
and analysis of its crash at https://lkml.org/lkml/2011/4/1/168

Use kzalloc within problematic drivers to ensure we have a zeroed struct
v4l2_subdev.

BugLink: http://bugs.launchpad.net/bugs/745213
Cc: <stable@kernel.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/upd64031a.c b/drivers/media/video/upd64031a.c
index f8138c7..1aab96a 100644
--- a/drivers/media/video/upd64031a.c
+++ b/drivers/media/video/upd64031a.c
@@ -230,7 +230,7 @@
 	v4l_info(client, "chip found @ 0x%x (%s)\n",
 			client->addr << 1, client->adapter->name);
 
-	state = kmalloc(sizeof(struct upd64031a_state), GFP_KERNEL);
+	state = kzalloc(sizeof(struct upd64031a_state), GFP_KERNEL);
 	if (state == NULL)
 		return -ENOMEM;
 	sd = &state->sd;