ppc/pnv: Remove unused XICSState reference

e6f7e110 "ppc/xics: remove the XICSState classes" got rid of
XICSState, this is just an leftover.
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: NCédric Le Goater <clg@kaod.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

include/hw/ppc/pnv_psi.h

@@ -28,8 +28,6 @@
 
 #define PSIHB_XSCOM_MAX         0x20
 
-typedef struct XICSState XICSState;
-
 typedef struct PnvPsi {
     SysBusDevice parent;