Fix sdk maven repo path
Fix sdk maven repo path

It should be extras/android/m2repository, however it was
set as extras/m2repository. We got lucky as Android Gradle
Plugin adds this path for us automatically, but we should not
rely on that.

Change-Id: Ief3d319345848ad2cd98705680e063c430c6e2f7
Test: ./gradlew tasks is still happy.

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