[HAX] Allow per-target dtbTool

 * Revert this when fixed

Change-Id: I97ecb0448ae7bd5859454be290c5dde6248b2859
Enable QCOM_BSP_LEGACY flag for pre-8974 targets

Change-Id: I895f1b1cbad0d260e1bca87ccb61e6194de023fd

Conflicts:
	core/qcom_target.mk