virt, sched: Add generic vCPU pinning support

Add generic virtualization support for pinning the current vCPU to a
specified physical CPU. As this operation isn't performance critical
(a very limited set of operations like BIOS calls and SMIs is expected
to need this) just add a hypervisor specific indirection.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Douglas_Warzecha@dell.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: chrisw@sous-sol.org
Cc: david.vrabel@citrix.com
Cc: hpa@zytor.com
Cc: jdelvare@suse.com
Cc: jeremy@goop.org
Cc: linux@roeck-us.net
Cc: pali.rohar@gmail.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1472453327-19050-3-git-send-email-jgross@suse.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>