backlight: lp855x: Drop ret variable in brightness change function

Fixes the following warning:

drivers/video/backlight/lp855x_bl.c:252:7: warning: variable 'ret' is used
uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]

Signed-off-by: Artur Weber <[e-mail]>
Fixes: 5145531be5fb ("backlight: lp855x: Catch errors when changing brightness")
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Reviewed-by: Daniel Thompson <[e-mail]>
Reviewed-by: Nathan Chancellor <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/video/backlight/lp855x_bl.c

···
 {
 	struct lp855x *lp = bl_get_data(bl);
 	int brightness = bl->props.brightness;
-	int ret;
 
 	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
 		brightness = 0;
 
 	if (lp->mode == PWM_BASED)
-		ret = lp855x_pwm_ctrl(lp, brightness,
+		return lp855x_pwm_ctrl(lp, brightness,
 				      bl->props.max_brightness);
 	else if (lp->mode == REGISTER_BASED)
-		ret = lp855x_write_byte(lp, lp->cfg->reg_brightness,
+		return lp855x_write_byte(lp, lp->cfg->reg_brightness,
 					(u8)brightness);
-
-	return ret;
+	return -EINVAL;
 }
 
 static const struct backlight_ops lp855x_bl_ops = {