OMAP3: igep00x0: Fix boot hang and add support for status LED.

Use the STATUS_LED APIs for indicating a boot progress instead of
show_boot_progress.

This patch also fixes a problem introduced with commit b3f4ca11 (dm: omap3:
Move to driver model for GPIO and serial). After that commit the board doesn't
boot. Looks like the problem is the gpio_request call inside the function
show_boot_progress.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>