davinci: mityomapl138: make file local data static

Most of the regulator data structures are local to the
board file, but not made static. Fix this.

Also make the nand partition table static.

This gets rid of all the sparse warnings for this file.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>