make-winpe.cmd does not support large (>32 GB) SD cards.

[dmcilvaney]

imx-iotcore/build/tools/make-winpe.cmd

Line 159 in 8dbde2b

echo create partition primary >> diskpart.txt

creates a partition as large as possible, but fat32 has an upper limit.

Need to also watch that a hard-coded size fits on smaller cards (ie 8GB)