Update dtc to 1.6.0 am: b734cfd607 am: 7713e835e7 am: a2d66c5f84 am: 7139aa3c99

Original change: https://android-review.googlesource.com/c/platform/external/dtc/+/1358703

Change-Id: I1d3a25b2768331be6ad6cd7a3695d80f6e7bfebb