ARM: davinci: add missing sentinels to GPIO lookup tables

Some GPIO lookup tables defined in davinci board files are missing
array sentinels. If an entry for given device cannot be found, this
will cause a kernel panic.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>