KVM: Increase user memory slots on x86 to 125

With the 3 private slots, this gives us a nice round 128 slots total.
The primary motivation for this is to support more assigned devices.
Each assigned device can theoretically use up to 8 slots (6 MMIO BARs,
1 ROM BAR, 1 spare for a split MSI-X table mapping) though it's far
more typical for a device to use 3-4 slots.  If we assume a typical VM
uses a dozen slots for non-assigned devices purposes, we should always
be able to support 14 worst case assigned devices or 28 to 37 typical
devices.
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -33,7 +33,7 @@
 
 #define KVM_MAX_VCPUS 254
 #define KVM_SOFT_MAX_VCPUS 160
-#define KVM_USER_MEM_SLOTS 32
+#define KVM_USER_MEM_SLOTS 125
 /* 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)