drivers: pwm: nRF5x: Use TIMER2 and PPI indices 14-19
drivers: pwm: nRF5x: Use TIMER2 and PPI indices 14-19

As the nRF5x BLE controller uses TIMER1, TIMER2 and PPI
indices 0-13 (and 14-15, if PA/LNA feature is enabled),
the software based PWM driver needing 6 PPI channels has
to use PPI indices outside the BLE controller used range.

Signed-off-by: Vinayak Kariappa Chettimada <e780c9f87dc729ad454f47292ad82c8652353064@nordicsemi.no>

zephyrproject-rtos/zephyr,punitvara/zephyr,galak/zephyr,zephyriot/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,punitvara/zephyr,kraj/zephyr,mbolivar/zephyr,finikorg/zephyr,kraj/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,punitvara/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,zephyriot/zephyr,explora26/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,kraj/zephyr,finikorg/zephyr,kraj/zephyr,Vudentz/zephyr,nashif/zephyr,ldts/zephyr,galak/zephyr,mbolivar/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,ldts/zephyr,aceofall/zephyr-iotos,Vudentz/zephyr,ldts/zephyr,explora26/zephyr,aceofall/zephyr-iotos,finikorg/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,kraj/zephyr,Vudentz/zephyr,zephyriot/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,finikorg/zephyr,ldts/zephyr,zephyriot/zephyr,punitvara/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,mbolivar/zephyr,galak/zephyr,punitvara/zephyr,finikorg/zephyr,mbolivar/zephyr,GiulianoFranchetto/zephyr