gesture_layer: fix long tap gesture has wrong timestamp.

gesture_layer: fix long tap gesture has wrong timestamp.

Summary:
The timestamp has 0 value when n_long_tap_start callback called.
Then timestamp is same on each n_long_tap_move callback functions.

For fix this bug, update timestamp before called state_set function.
Also update timestamp in every timeout.

Test Plan:
Run test_gesture_layer2.c
Print timestamp in every n_long_tap_XXX callback.

Reviewers: tasn, cedric

Differential Revision: https://phab.enlightenment.org/D3144

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>