power: supply: max77650: Make max77650_charger_disable() return void
The return value of max77650_charger_disable() is ignored by all but one
caller. That one caller propagates the error code in the platform driver's
remove function. The only effect of that is that the driver core emits
a generic error message (but still removes the device). As
max77650_charger_disable() already emits an error message, this can better
be changed to return zero.
This is a preparation for making struct platform_driver::remove return
void, too.