m25p80.c: Return state to IDLE after COLLECTING

Default to moving back to the IDLE state after the COLLECTING_DATA
state. For a well behaved guest this patch has no consequence, but
A bad guest could crash QEMU by using one of the erase commands
followed by a longer than 5 byte argument (undefined behaviour).
Signed-off-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: NEdgar E. Iglesias <edgar.iglesias@gmail.com>

hw/m25p80.c

@@ -358,6 +358,8 @@ static void complete_collecting_data(Flash *s)
     s->cur_addr |= s->data[1] << 8;
     s->cur_addr |= s->data[2];
 
+    s->state = STATE_IDLE;
+
     switch (s->cmd_in_progress) {
     case DPP:
     case QPP: