[intel] Exclude time spent in hypervisor from profiling

When profiling, exclude any time spent inside the hypervisor
responding to our MMIO accesses.  This substantially reduces the
variance accumulated on many other profilers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/intel.c

 		profile_start ( &intel_vm_refill_profiler );
 		writel ( rx_tail, intel->regs + intel->rx.reg + INTEL_xDT );
 		profile_stop ( &intel_vm_refill_profiler );
+		profile_exclude ( &intel_vm_refill_profiler );
 	}
 }
 
 	profile_start ( &intel_vm_tx_profiler );
 	writel ( tx_tail, intel->regs + intel->tx.reg + INTEL_xDT );
 	profile_stop ( &intel_vm_tx_profiler );
+	profile_exclude ( &intel_vm_tx_profiler );
 
 	DBGC2 ( intel, "INTEL %p TX %d is [%llx,%llx)\n", intel, tx_idx,
 		( ( unsigned long long ) address ),
 	profile_start ( &intel_vm_poll_profiler );
 	icr = readl ( intel->regs + INTEL_ICR );
 	profile_stop ( &intel_vm_poll_profiler );
+	profile_exclude ( &intel_vm_poll_profiler );
 	if ( ! icr )
 		return;