KVM: Make KVM_PRIVATE_MEM_SLOTS optional

Seems like everyone copied x86 and defined 4 private memory slots
that never actually get used.  Even x86 only uses 3 of the 4.  These
aren't exposed so there's no need to add padding.

Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c7df6ff..51d5210 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -34,8 +34,8 @@
 #define KVM_MAX_VCPUS 254
 #define KVM_SOFT_MAX_VCPUS 160
 #define KVM_USER_MEM_SLOTS 32
-/* memory slots that does not exposed to userspace */
-#define KVM_PRIVATE_MEM_SLOTS 4
+/* memory slots that are not exposed to userspace */
+#define KVM_PRIVATE_MEM_SLOTS 3
 #define KVM_MEM_SLOTS_NUM (KVM_USER_MEM_SLOTS + KVM_PRIVATE_MEM_SLOTS)
 
 #define KVM_MMIO_SIZE 16