prebuilt: backuptool: Drop addond version check on A-only

 * This check was supposed to check whether the script
   addon.d version was lower than backuptool's

 * Given that the backuptool addon.d version is 1, this
   isn't going to happen ever making this check completely
   unuseful

Change-Id: I2464749b52bf4e8825e0b4ef42500ee7d3bbfa61