kvm: make KVM_MMU_AUDIT help text more readable

Make KVM_MMU_AUDIT kconfig help text readable and collapse
two spaces between words down to one space.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>