KVM: selftests: memslot_perf_test: increase guest sync timeout

When memslot_perf_test is run nested, first iteration of test_memslot_rw_loop
testcase, sometimes takes more than 2 seconds due to build of shadow page tables.

Following iterations are fast.

To be on the safe side, bump the timeout to 10 seconds.

Signed-off-by: Maxim Levitsky <[e-mail]>
Tested-by: Liam Merwick <[e-mail]>
Reviewed-by: Liam Merwick <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>

tools/testing/selftests/kvm/memslot_perf_test.c

···
  */
 static noinline void host_perform_sync(struct sync_area *sync)
 {
-	alarm(2);
+	alarm(10);
 
 	atomic_store_explicit(&sync->sync_flag, true, memory_order_release);
 	while (atomic_load_explicit(&sync->sync_flag, memory_order_acquire))