media: isp: fix a warning about a wrong struct initializer

As sparse complains:
	drivers/media/platform/omap3isp/isp.c:303:39: warning: Using plain integer as NULL pointer

when a struct is initialized with { 0 }, actually the first
element of the struct is initialized with zeros, initializing the
other elements recursively. That can even generate gcc warnings
on nested structs.

So, instead, use the gcc-specific syntax for that (with is used
broadly inside the Kernel), initializing it with {};
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/omap3isp/isp.c

@@ -300,7 +300,7 @@ static struct clk *isp_xclk_src_get(struct of_phandle_args *clkspec, void *data)
 static int isp_xclk_init(struct isp_device *isp)
 {
 	struct device_node *np = isp->dev->of_node;
-	struct clk_init_data init = { 0 };
+	struct clk_init_data init = {};
 	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i)