lp8727_charger: Add terminating entry for i2c_device_id table

The i2c_device_id table is supposed to be zero-terminated.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>