dts: nordic: Use PPIs 0-5 consistently for SW PWM

Use PPIs 0-5 consistently across nRF51x and nRF52x for SW
PWM driver. Bluetooth LE controller's use of PPI has been
adjusted to use PPI 6-19 based on features enabled.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
8 files changed