[#1972] cli: Fix lifetime flag in the `lock` command

That part of the code was refactored incorrectly.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-cli/modules/object/lock.go

@@ -63,9 +63,11 @@ var objectLockCmd = &cobra.Command{
 			currEpoch, err := internalclient.GetCurrentEpoch(ctx, endpoint)
 			common.ExitOnErr(cmd, "Request current epoch: %w", err)
 
-			exp += currEpoch
+			exp = currEpoch + lifetime
 		}
 
+		common.PrintVerbose("Lock object will expire at %d epoch", exp)
+
 		var expirationAttr objectSDK.Attribute
 		expirationAttr.SetKey(objectV2.SysAttributeExpEpoch)
 		expirationAttr.SetValue(strconv.FormatUint(exp, 10))