Improvements in STM32 PWM low level driver
stm32_pwm: remove some impossible PWM configurations
stm32_pwm: support for complementary outputs
stm32_pwm: deadtime configuration
stm32_pwm: output polarity and IDLE state configuration
nucleo-f302r8: pwm support
stm32f429i-disco: pwm support
configs: update some configurations according to changes in STM32 PWM driver
Approved-by: GregoryN <gnutt@nuttx.org>
