samples: blinky_pwm: Fix sample for rpi_pico
samples: blinky_pwm: Fix sample for rpi_pico

The RP2040 needs a DTS overlay for the PWM to work with the
blinky_pwm examples. This commit adds the required overlay.

Signed-off-by: Yonatan Schachter <c03ea33f3e5919b7d64cfd097e68ce03a1b1a328@gmail.com>

galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr