create_builddir: add hw_imx53 (TrustZone) target

Until now, the HW platform support for the TrustZone features of the
i.MX53 boards could only be used, when adding a "trustzone" SPEC variable
manually. This commit adds a create_builddir target for HW i.MX53 with
TrustZone features enabled, fo convenience reasons.
run: wait some time before loading images via JTAG

When powering up the device it sometimes needs some seconds before the
bootloader prepared the board to use JTAG uploading.