power: supply: lp8788: make const array name static

Don't populate the read-only array name on the stack but instead make
it static. Since the data and the pointers don't change also add in
a missing const. Also makes the object code a little smaller.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>