utils: Modify data type for propagation of timestamps.
utils: Modify data type for propagation of timestamps.

Change from G_TYPE_STRING data type for timestamps propagation to two
G_TYPE_ULONG data type used for tv_sec and tv_usec.

Signed-off-by: Daniel Diaz <ed054987dd20aebbd314fbb0d175066628f13717@ti.com>

mrchapp/gst-goo,mrchapp/gst-goo