Clean up v17-leanback makefile
Clean up v17-leanback makefile

Test: docs target builds successfully
Change-Id: Icf2ea1c372559476181836c0362d799a5c556c0d

AndroidX/androidx,AndroidX/androidx,aosp-mirror/platform_frameworks_support,AndroidX/androidx,aosp-mirror/platform_frameworks_support,aosp-mirror/platform_frameworks_support,androidx/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx