ANDROID: KVM: arm64: Add support for nVHE hyp events

Following the introduction of tracing buffers for the nVHE hypervisor,
add the support to declare in-hypervisor events.

Hypervisor events are declared into kvm_hypevents.h and can be called
with trace_<event_name>().

hyp_enter and hyp_exit events are provided as an example.

Bug: 229972309
Co-authored-By: Nikita Ioffe <ioffe@google.com>
Change-Id: I42d110fece793112d30530154aab49049b7fa520
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Nikita Ioffe <ioffe@google.com>