imx-drm: imx-tve: Provide __acquires/__releases annotation

Fix the following sparse warnings:

drivers/staging/imx-drm/imx-tve.c:133:13: warning: context imbalance in 'tve_lock' - wrong count at exit
drivers/staging/imx-drm/imx-tve.c:139:13: warning: context imbalance in 'tve_unlock' - unexpected unlock

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/imx-drm/imx-tve.c

@@ -131,12 +131,14 @@ struct imx_tve {
 };
 
 static void tve_lock(void *__tve)
+__acquires(&tve->lock)
 {
 	struct imx_tve *tve = __tve;
 	spin_lock(&tve->lock);
 }
 
 static void tve_unlock(void *__tve)
+__releases(&tve->lock)
 {
 	struct imx_tve *tve = __tve;
 	spin_unlock(&tve->lock);