configs: stm32mp13: Enable MFD timer and PWM for stm32mp13_defconfig
Enable the following configs:
* CONFIG_MFD_STM32_TIMERS: enables support for the STM32 multifunction
timer
* CONFIG_DM_PWM: enables support for pulse-width modulation devices
* CONFIG_CMD_PWM: enables 'pwm' command to control PWM channels
* CONFIG_PWM_STM32: enables support for the STM32 PWM devices