Stop requiring miner address / sector size for lotus client commP

At present, and at least for the medium term (even with the transition to NSE)
the structure of a piece (and thus commP) will remain identical for every size
of sector.

The offline deal flow would benefit greatly if the `lotus client commP`
interface is able to calculate commP without having access to a fully synced
sync, or without even being online.

This is particularly important for filecoin-discover, as we want to allow
miners to spot-check their purchased HDDs, way before they need to accept
the mainnet deal proposals.

See comment/links in node/impl/client/client.go for details on code flow

cli/client.go

@@ -174,7 +174,7 @@ var clientDropCmd = &cli.Command{
 var clientCommPCmd = &cli.Command{
 	Name:      "commP",
 	Usage:     "Calculate the piece-cid (commP) of a CAR file",
-	ArgsUsage: "[inputFile minerAddress]",
+	ArgsUsage: "[inputFile]",
 	Flags: []cli.Flag{
 		&CidBaseFlag,
 	},
@@ -186,16 +186,11 @@ var clientCommPCmd = &cli.Command{
 		defer closer()
 		ctx := ReqContext(cctx)
 
-		if cctx.Args().Len() != 2 {
-			return fmt.Errorf("usage: commP <inputPath> <minerAddr>")
+		if cctx.Args().Len() != 1 {
+			return fmt.Errorf("usage: commP <inputPath>")
 		}
 
-		miner, err := address.NewFromString(cctx.Args().Get(1))
-		if err != nil {
-			return err
-		}
-
-		ret, err := api.ClientCalcCommP(ctx, cctx.Args().Get(0), miner)
+		ret, err := api.ClientCalcCommP(ctx, cctx.Args().Get(0))
 		if err != nil {
 			return err
 		}