Add the mma8451 driver back.

tannewt · tannewt · commit a81635eeba7b · 2018-03-05T14:44:41.000-08:00
diff --git a/libraries/drivers/mma8451 b/libraries/drivers/mma8451
@@ -0,0 +1 @@
+Subproject commit f389f1f57f5567a8e23901346f264285f432a061
