elan: restart after short swipe needs access to fp_img_dev

Not sure what but it looks like something broke re-entering capture loop after a short swipe. This is the fix

diff --git a/libfprint/drivers/elan.c b/libfprint/drivers/elan.c
index ed474b0..e4cf93e 100644
--- a/libfprint/drivers/elan.c
+++ b/libfprint/drivers/elan.c
@@ -39,6 +39,7 @@
 #define FP_COMPONENT "elan"
 
 #include "drivers_api.h"
+#include "fp_internal.h"
 #include "elan.h"
 
 #define dbg_buf(buf, len)                                     \
@@ -472,8 +473,10 @@ static void stop_capture_complete(fpi_ssm *ssm, struct fp_dev *_dev, void *user_
                 * deactivate, try to re-enter the capture loop. Since state change is
                 * async, there's still a chance to be deactivated by another pending
                 * event. */
-               if (elandev->dev_state_next != IMGDEV_STATE_INACTIVE)
+               if (elandev->dev_state_next != IMGDEV_STATE_INACTIVE) {
+                       dev->action_state = IMG_ACQUIRE_STATE_AWAIT_FINGER_ON;
                        dev_change_state(dev, IMGDEV_STATE_AWAIT_FINGER_ON);
+    }
 
        } else if (error != -ECANCELED)
                fpi_imgdev_abort_scan(dev, error);

Otherwise the subsequent fpi_imgdev_report_finger_status(dev, TRUE) fails ("ignoring status report") and everything hangs. The problem is that it needs fp_internal.h which isn't for drivers, right? Here are the possible solutions I see:

1. Expose fp_img_dev. I guess it's hidden for a reason, so..

2. Make fpi_imgdev_report_finger_status (or fpi_drvcb_report_X_result) actually manage action_state all the time, not only during IMG_ACTION_ENROLL. This makes sense to me because if it's called with FALSE and action_state = IMG_ACQUIRE_STATE_AWAIT_FINDER_OFF, then action_state should advance to a different state, shouldn't it?

3. Disable short swipe checks in elan and make it fail instead. I only have a VFS5011 device to compare and it seems to do just that. It might just be that "short swipe" functionality isn't yet ready to be used by the drivers.