IB/hfi1: Add a safe wrapper for _rcd_get_by_index

hfi1_rcd_get_by_index assumes that the given index is in the correct
range.  In most cases this is correct because the index is bounded by
a loop.  For these cases, adding a range check to the function is
redundant.

For the use case that is not bounded by the loop range, a _safe wrapper
function is needed to validate the index before accessing the rcd array.

Add a _safe wrapper to _get_by_index to validate the index range.

Update appropriate call sites with the new _safe function.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/chip.c

@@ -13065,7 +13065,7 @@ static int request_msix_irqs(struct hfi1_devdata *dd)
 			me->type = IRQ_SDMA;
 		} else if (first_rx <= i && i < last_rx) {
 			idx = i - first_rx;
-			rcd = hfi1_rcd_get_by_index(dd, idx);
+			rcd = hfi1_rcd_get_by_index_safe(dd, idx);
 			if (rcd) {
 				/*
 				 * Set the interrupt register and mask for this