ti-st: handle null allocation return correctly.

static analysis with smatch picked up the following error:

get_platform_data() error: potential null dereference 'dt_pdata'.
  (kzalloc returns null)

Instead, the code should return NULL to avoid the following null
pointer deference.  Also, remove the error message as it is
redundant, the caller emits an error message to alert of a
failure anyhow.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/ti-st/st_kim.c

@@ -752,9 +752,8 @@ static struct ti_st_plat_data *get_platform_data(struct device *dev)
 	int len;
 
 	dt_pdata = kzalloc(sizeof(*dt_pdata), GFP_KERNEL);
-
 	if (!dt_pdata)
-		pr_err("Can't allocate device_tree platform data\n");
+		return NULL;
 
 	dt_property = of_get_property(np, "dev_name", &len);
 	if (dt_property)