drivers: usb_dc_rpi_pico: handling of data toggle after endpoint setup

The previous behaviour led to an issue where we already expected data1
on the first transfer instead of data0. The DesignWare USB DC actually
implements the same behaviour. Also, the next_pid flag has to be reset
on setting up the endpoint.
Fixes #66283.

Signed-off-by: Manuel Aebischer <manuel.aebischer@netmodule.com>