x86: 64-bit defconfig remake

The current x86_64_defconfig contains a number of nonexistent
symbols. Lets fix it.
Signed-off-by: NCyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>