KVM: PPC: Book3S HV: Add H_VIRT mapping for tracing exits

The macro kvm_trace_symbol_exit is used for providing the mappings
for the trap vectors and their names. Add mapping for H_VIRT so that
trap reason is displayed as string instead of a vector number when using
the kvm_guest_exit tracepoint.

Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250516121225.276466-1-gautam@linux.ibm.com