Fix some event ref count error.
Fix some event ref count error.

Move the event add ref to function cl_event_new_enqueue_callback for clear.
Also need add the wait user events' ref count.

Signed-off-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>
Reviewed-by: "Luo, Xionghu" <c3dafbeb50547b880155fb36e6f40d38b44f6611@intel.com>

wdv4758h/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet,zhenyw/beignet,wdv4758h/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet,zhenyw/beignet,zhenyw/beignet,wdv4758h/beignet,freedesktop-unofficial-mirror/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet