cm: Switch to the staging/cm-14.0 CMSDK prebuilts branch

This is the up-to-date, staging branch.

Change-Id: Ia2c634b9787e9ac825cd404d03dacc435ad75f71

snippets/cm-14.0.xml

@@ -65,7 +65,7 @@
   <project path="packages/services/ThemeManagerService" name="CyanogenMod/android_packages_services_ThemeManagerService" />
   <project path="packages/services/WeatherService" name="CyanogenMod/android_packages_services_WeatherService" />
   <project path="packages/themes/HexoLibre" name="CyanogenMod/android_packages_themes_HexoLibre" groups="themes" />
-  <project path="prebuilts/cmsdk" name="CyanogenMod/android_prebuilts_cmsdk" clone-depth="1" revision="master" />
+  <project path="prebuilts/cmsdk" name="CyanogenMod/android_prebuilts_cmsdk" clone-depth="1" />
   <project path="system/extras/su" name="CyanogenMod/android_system_extras_su" />
   <project path="vendor/cm" name="CyanogenMod/android_vendor_cm" />
   <project path="vendor/cmsdk" name="CyanogenMod/cm_platform_sdk" />