Allow vmexit profiling utility to run

Allow direct access to the cycle counter from VMs and just return
gracefully on an hvc #0 call.

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
KVM: ARM: Introduce more trace events

We would like to see some more detailed trace events for performance
profiling.

Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
KVM: ARM: Measuring hack!!!

Warning: Not for human consumption.