drivers: pwm: mcux_ftm: add support for inverted polarity pwm signals
drivers: pwm: mcux_ftm: add support for inverted polarity pwm signals

Add support for specifying the PWM signal polarity through flags to
the NXP Kinetis FlexTimer (FTM) PWM driver.

Prior to this change the FTM PWM driver always produced inverted
polarity (active-low) PWM signals.

Signed-off-by: Henrik Brix Andersen <24a3f13c22635bab658e39fc5f1e63c575328aae@vestas.com>

galak/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr