drivers: clock_control: rpi_pico: Add support for the RP2350.

Add support for SoC-specific clock ids and update the initialization
function to support the existing RP2040 and add support for the RP2350.

clock_control_rpi_pico.c uses numerical values for clock ids taken from
rpi_pico_clock.h which are the "clock generator". For the RP2350 these
values are different for some of the same logical clock sources, as well
as the RP2040 and RP2350 having different clock sources available.

Signed-off-by: Andrew Featherstone <andrew.featherstone@gmail.com>