Fix length normilization bug in rsMatrixLoadRotate.

Change-Id: Ibdc1a64f2db6110acd971f8cacd6b1f9c09b02de
diff --git a/libs/rs/rsMatrix.cpp b/libs/rs/rsMatrix.cpp
index 2f21405..94eef13 100644
--- a/libs/rs/rsMatrix.cpp
+++ b/libs/rs/rsMatrix.cpp
@@ -73,7 +73,7 @@
     s = sinf(rot);
 
     const float len = sqrtf(x*x + y*y + z*z);
-    if (!(len != 1)) {
+    if (len != 1) {
         const float recipLen = 1.f / len;
         x *= recipLen;
         y *= recipLen;