meta-facebook: fix up new shellcheck warnings

New docker container is flagging some issues in this shell script:

```
SC2004 (style): $/${} is unnecessary on arithmetic variables.
SC2317 (info): Command appears to be unreachable. Check usage (or ignore if invoked indirectly).
```

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I9806a097ca417d8677374efd666f2a8865a0a2fd
diff --git a/meta-facebook/recipes-phosphor/datetime/phosphor-time-manager/set-bmc-time-from-host b/meta-facebook/recipes-phosphor/datetime/phosphor-time-manager/set-bmc-time-from-host
index 40b3b8c..8d6d3ae 100644
--- a/meta-facebook/recipes-phosphor/datetime/phosphor-time-manager/set-bmc-time-from-host
+++ b/meta-facebook/recipes-phosphor/datetime/phosphor-time-manager/set-bmc-time-from-host
@@ -72,7 +72,7 @@
 
         if [[ $(echo "$multi_host_time_result" | awk '{ print NF }') -eq 18 ]];
         then
-            echo "syncing up host " $index " date time with bmc..."
+            echo "syncing up host " "$index" " date time with bmc..."
             date -s @$((0x$(echo "$multi_host_time_result" | \
             awk '{printf "%02x%02x%02x%02x",$18,$17,$16,$15}')))
             sync