tests: driver: pwm: pwm_api: Enable flexio_pwm function on pwm_api case

Enable flexio clock in soc.c file
Add mimxrt1180_evk_flexio_pwm.overlay：
- Configure flexio2_d2 pins
- enable flexio2_pwm
- disable default watchdog tpm5

Signed-off-by: Lucien Zhao <lucien.zhao@nxp.com>