ARM: tegra: seaboard: Don't gpio_request() ISL29018_IRQ

Don't call gpio_request() or gpio_direction_input() for ISL29018_IRQ.
This pin is only used as an IRQ, and hence no GPIO configuration should
be necessary; the GPIO/IRQ driver should (and does) perform any required
setup when the IRQ is requested.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Olof Johansson <olof@lixom.net>