Add the missing dependency on payload generation script.

For A/B OTAs, ota_from_target_files.py calls brillo_update_payload
script to generate the payload entry in an A/B OTA package.

Bug: 37443093
Test: lunch aosp_marlin-userdebug && rm
      out/host/linux-x86/bin/brillo_update_payload && m otapackage
Change-Id: I3845786b6c934c709f32e12a63cd6ea1f303d380