IB/ehca: Rework destroy_eq()

The ibmebus_free_irq() function, which might sleep, was called with
interrupts disabled.  To fix this, make sure that no interrupts are
running by killing the interrupt tasklet.  Also lock the
shca_list_lock to protect against the poll_eqs_timer running
concurrently.

Signed-off-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h
index c825142..0136abd 100644
--- a/drivers/infiniband/hw/ehca/ehca_classes.h
+++ b/drivers/infiniband/hw/ehca/ehca_classes.h
@@ -375,6 +375,7 @@
 extern rwlock_t ehca_cq_idr_lock;
 extern struct idr ehca_qp_idr;
 extern struct idr ehca_cq_idr;
+extern spinlock_t shca_list_lock;
 
 extern int ehca_static_rate;
 extern int ehca_port_act_time;