isp1704_charger: Set isp->dev before anything needs it

isp1704_test_ulpi() is the first place that needs isp->dev
member, so it must be set before calling the function.

Signed-off-by: Heikki Krogerus <heikki.krogerus@nokia.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>