exynos5: Enable tps65090 on exynos5-dt

The TPS65090 pmic chip can be on exynos5250 boards. Therefore,
select the appropriate config option for TPS65090 devices.

This commit should really use exynos5-dt.c, when it is available.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>