[U-Boot] video: ipu_common: fix build error

[Fabio Estevam]

Hi Eric,

On Mon, Sep 4, 2017 at 11:49 PM, Eric Nelson <eric at nelint.com> wrote:
> Hi Peng,
>
> Can you tell that I'm hunting a bug in an old version?
>
> I'm seeing a **very** intermittent regression between U-Boot
> versions 2015.07 and 2016.05 and happened to spot something
> in this patch.

Just curious: how does the regression manifest itself?