selftests: KVM: Add exponent check for boolean stats

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2119111



commit dd4d1c3b
Author: Oliver Upton <oupton@google.com>
Date:   Tue Jul 19 14:31:34 2022 +0000

    selftests: KVM: Add exponent check for boolean stats

    The only sensible exponent for a boolean stat is 0. Add a test assertion
    requiring all boolean statistics to have an exponent of 0.

Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
    Message-Id: <20220719143134.3246798-4-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>