tests: dac: Enable dac_api test on mimxrt1180_evk

1.Enable dac_api test on mimxrt1180_evk
2.Reorganized the test_dac.c file so that the same
dac configuration items are placed under the one
conditional macro.

Signed-off-by: Zhaoxiang Jin <Zhaoxiang.Jin_1@nxp.com>