motorola-osprey has a very clunky name at the moment "Motorola Moto G
3rd gen. (2015)". The device was mostly just called "Motorola Moto G"
by Motorola, so it is hard to choose a fitting (but unique) name.
In the postmarketOS wiki it is called "Motorola Moto G 2015" so let's
just drop the "3rd gen." in the pmOS device package as well.
Also make the deviceinfo consistent with harpia while at it.