spring cleaning: shieldtablet

Change-Id: Ib80ecf8e0517071e5d8d55ae0ae29b18deb5f002
peregrine: never actually supported?

Change-Id: I9148710963b8dcc728aea556537f19bc2c948932
hlte: tmo and spr exist... 2 of the 3 hltes we had don't

Change-Id: Ifdc6323b9f47838ffbdb8e6490f1d1a4988e019a