target/ppc: reset reservation in do_rfi()

For transitioning back to userspace after the interrupt.
Suggested-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NNikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

target/ppc/excp_helper.c

@@ -995,6 +995,9 @@ static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong msr)
      */
     cs->interrupt_request |= CPU_INTERRUPT_EXITTB;
 
+    /* Reset the reservation */
+    env->reserve_addr = -1;
+
     /* Context synchronizing: check if TCG TLB needs flush */
     check_tlb_flush(env, false);
 }