KVM: convert slots_lock to a mutex

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4b433de..6a74246 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -605,7 +605,7 @@
 	.write    = speaker_ioport_write,
 };
 
-/* Caller must have writers lock on slots_lock */
+/* Caller must hold slots_lock */
 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 {
 	struct kvm_pit *pit;