gpu: ipu-v3: ipu-dc: Remove unused 'di' variable

The 'di' variable is never used inside ipu_dc_enable_channel(),
so just remove it.

This fixes the following build warning with W=1:

drivers/gpu/ipu-v3/ipu-dc.c: In function 'ipu_dc_enable_channel':
drivers/gpu/ipu-v3/ipu-dc.c:252:6: warning: variable 'di' set but not used [-Wunused-but-set-variable]
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/ipu-dc.c

@@ -249,11 +249,8 @@ EXPORT_SYMBOL_GPL(ipu_dc_enable);
 
 void ipu_dc_enable_channel(struct ipu_dc *dc)
 {
-	int di;
 	u32 reg;
 
-	di = dc->di;
-
 	reg = readl(dc->base + DC_WR_CH_CONF);
 	reg |= DC_WR_CH_CONF_PROG_TYPE_NORMAL;
 	writel(reg, dc->base + DC_WR_CH_CONF);