device-motorola-rtwo: depend on android-tools, not mkbootimg

boot-deploy needs the AOSP mkbootimg (from android-tools) to build the
header v4 boot.img + vendor_boot.img pair; mkbootimg-osm0sis does not
handle GKI/vendor_boot. Matches the other header-v4 devices (Pixel 6).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QF5HebjUsRaxbW4cBX6HJP

device/testing/device-motorola-rtwo/APKBUILD

@@ -8,8 +8,8 @@ url="https://postmarketos.org"
 arch="aarch64"
 license="MIT"
 depends="
+	android-tools
 	linux-postmarketos-qcom-sm8550
-	mkbootimg
 	postmarketos-base
 	soc-qcom
 	"