When configuring a new project, you can choose which kits to use. But none has the name iphoneos-clang Qt 5.5.1 for iOS. Instead you can only choose iphoneos-clang Qt 5.5.0 for iOS. But if looking in preferences, you can see that iphoneos-clang Qt 5.5.0 for iOS is actually using QT 5.5.1 for iOS.
Found during package testing of Qt-5.5.1