power: supply: ltc3651-charger: Fix device name

There never was a device called LTC3651, it always was just LT3651.
This circumstance makes it pretty difficult to identify what this
driver is meant to control.channges since

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>