KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number

Commit b005255e12 ("KVM: PPC: Book3S HV: Context-switch new POWER8
SPRs") added a definition of KVM_REG_PPC_WORT with the same register
number as the existing KVM_REG_PPC_VRSAVE (though in fact the
definitions are not identical because of the different register sizes.)

For clarity, this moves KVM_REG_PPC_WORT to the next unused number,
and also adds it to api.txt.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

Documentation/virtual/kvm/api.txt

@@ -1873,6 +1873,7 @@ registers, find a list below:
   PPC   | KVM_REG_PPC_PPR	| 64
   PPC   | KVM_REG_PPC_ARCH_COMPAT 32
   PPC   | KVM_REG_PPC_DABRX     | 32
+  PPC   | KVM_REG_PPC_WORT      | 64
   PPC   | KVM_REG_PPC_TM_GPR0	| 64
           ...
   PPC   | KVM_REG_PPC_TM_GPR31	| 64