tests: drivers: pwm: add pwm configuration for mke17z

Add pwm configuration for frdm_ke17z and frdm_ke17z512 boards.
Set the alias of pwm-0 to ftm2 and test the pwm_api sample.
Update the ftm and pwt configuration to test pwm_loopback sample.

Signed-off-by: Anke Xiao <anke.xiao@nxp.com>