drm: mali-dp: Clear the config_valid flag before using it in wait_event.

config_valid variable is used to signal the activation of the CVAL
request when the vsync interrupt has fired. malidp_set_and_wait_config_valid()
uses the variable in wait_event_interruptible_timeout without clearing it
first, so the wait is skipped.
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

drivers/gpu/drm/arm/malidp_drv.c

@@ -42,6 +42,7 @@ static int malidp_set_and_wait_config_valid(struct drm_device *drm)
 	struct malidp_hw_device *hwdev = malidp->dev;
 	int ret;
 
+	atomic_set(&malidp->config_valid, 0);
 	hwdev->set_config_valid(hwdev);
 	/* don't wait for config_valid flag if we are in config mode */
 	if (hwdev->in_config_mode(hwdev))