boards: correct default target type for the MIMXRT1160-EVK (#1429)
boards: correct default target type for the MIMXRT1160-EVK (#1429)

The previously specified 'mimxrt1160_cm7' does not exist as a builtin
target type. Now using 'mimxrt1166xxxxx' from the relevant DFP.
flit/pyOCD,pyocd/pyOCD,flit/pyOCD,pyocd/pyOCD