target-ppc: Add helper for KVM_PPC_RTAS_DEFINE_TOKEN

target-ppc: Add helper for KVM_PPC_RTAS_DEFINE_TOKEN

Recent PowerKVM allows the kernel to intercept some RTAS calls from the
guest directly.  This is used to implement the more efficient in-kernel
XICS for example.  qemu is still responsible for assigning the RTAS token
numbers however, and needs to tell the kernel which RTAS function name is
assigned to a given token value.  This patch adds a convenience wrapper for
the KVM_PPC_RTAS_DEFINE_TOKEN ioctl() which is used for this purpose.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>