isp1704_charger: Fix missing check

A segfault happens if there's no board information.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Acked-by: Heikki Krogerus <krohei@gmail.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
1 file changed