soc: rpi_pico: Set the default `SYS_CLOCK_HW_CYCLES_PER_SEC` from dt

Avoid the individual `CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC` for each
board instead to referencing the dt value.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>
16 files changed