drivers: sensor: vcnl4040: Update driver to use gpio_dt_spec

Move driver to use gpio_dt_spec for GPIO interrupt handling.

Added check to vcnl4040_trigger_set to handle case of trigger
mode enabled but the devicetree doesn't have an int_gpios property.

Also, moved up the checking/handling of gpio port device in
vcnl4040_trigger_init so that if we error out its before we
setup any threads and such.

Signed-off-by: Kumar Gala <galak@kernel.org>