samples: drivers: adc: enbale test for mr_canhubk3

Enable all channels that available connector on board.
ADC0 channel 6 on precision group with normal end chain
callback.
ADC1 channel 2 on precision group with normal end of
conversion callback.
ADC2 channels 3, 4, 5 on precision group with normal end
of conversion callback.

Signed-off-by: Cong Nguyen Huu <cong.nguyenhuu@nxp.com>
3 files changed