drivers/video: add kmalloc NULL tests

drivers/video: add kmalloc NULL tests

Check that the result of kmalloc is not NULL before passing it to other
functions.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression *x;
identifier f;
constant char *C;
@@

x = \(kmalloc\|kcalloc\|kzalloc\)(...);
... when != x == NULL
    when != x != NULL
    when != (x || ...)
(
kfree(x)
|
f(...,C,...,x,...)
|
*f(...,x,...)
|
*x->f
)
// </smpl>

[akpm@linux-foundation.org: convert to kstrdup() as well]
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>