pseries: Fix some small errors in XICS logic

Under certain circumstances the emulation for the pseries "XICS" interrupt
controller was clearing a pending interrupt from the XISR register, without
also clearing the corresponding priority variable.  This will cause
problems later when can trigger sanity checks in the under-development
in-kernel XICS implementation.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/xics.c

@@ -101,6 +101,7 @@ static void icp_set_cppr(struct icp_state *icp, int server, uint8_t cppr)
         if (XISR(ss) && (cppr <= ss->pending_priority)) {
             old_xisr = XISR(ss);
             ss->xirr &= ~XISR_MASK; /* Clear XISR */
+            ss->pending_priority = 0xff;
             qemu_irq_lower(ss->output);
             ics_reject(icp->ics, old_xisr);
         }
@@ -127,6 +128,7 @@ static uint32_t icp_accept(struct icp_server_state *ss)
 
     qemu_irq_lower(ss->output);
     ss->xirr = ss->pending_priority << 24;
+    ss->pending_priority = 0xff;
 
     trace_xics_icp_accept(xirr, ss->xirr);