iOS: Fix header names.

The include statements for the headers UIKit was written UiKit
(with lower-case 'i') causing build failure on systems with case
sensitive file-systems.

Change-Id: I7a3062ad8f0e9a0ee8a4b3f06465222332bb6c14
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>