AppleTV: Improving the AppleTV kernel configuration

General changes include:
 - Using a uniprocessor kernel
 - Move all hardware functionality (not provided out-of-the-box) to modules
 - Disable hardware functionality that AppleTV hardware will never support (e.g. MPPARSE, PAT, HW random generator)
 - Added hardware functionality in-kernel that AppleTV hardware does have (e.g. watchdog support)
 - Enabled power management features supported by AppleTV

Changes not included (yet):
 - Suspend/Hibernate functionality
 - Tracing capabilities

**Update**: @sraue @chewitt I think we are ready to pull this. Even though we have some debugging features enabled, I haven't encountered any impact on performance and only slight impact on RAM usage.