KVM: stats: Fix value for KVM_STATS_UNIT_MAX for boolean stats

KVM: stats: Fix value for KVM_STATS_UNIT_MAX for boolean stats

commit 1b870fa5573e ("kvm: stats: tell userspace which values are
boolean") added a new stat unit (boolean) but failed to raise
KVM_STATS_UNIT_MAX.

Fix by pointing UNIT_MAX at the new max value of UNIT_BOOLEAN.

Fixes: 1b870fa5573e ("kvm: stats: tell userspace which values are boolean")
Reported-by: Janis Schoetterl-Glausch <[email protected]>
Signed-off-by: Oliver Upton <[email protected]>
Message-Id: <20220719125229.2934273[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>