samples: sensor: mcux_acmp: add acmp configuration for ke17z

Add acmp pinctrl configuration to support ACMP driver for NXP frdm_ke17z
and frdm_ke17z512, tested 'sample.sensor.mcux_acmp' case.
Update the index.rst to add acmp description for ke17z.

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