drm_hwcomposer: Enable readability-math-missing-parentheses tidy check

... and fix all related warnings.

Change-Id: Ic122235524e567f2be5040ae7742fefb531a9766
Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/drm/ResourceManager.cpp b/drm/ResourceManager.cpp
index 9c68816..c866263 100644
--- a/drm/ResourceManager.cpp
+++ b/drm/ResourceManager.cpp
@@ -124,7 +124,7 @@
   struct timespec ts {};
   clock_gettime(CLOCK_MONOTONIC, &ts);
   constexpr int64_t kNsInSec = 1000000000LL;
-  return int64_t(ts.tv_sec) * kNsInSec + int64_t(ts.tv_nsec);
+  return (int64_t(ts.tv_sec) * kNsInSec) + int64_t(ts.tv_nsec);
 }
 
 void ResourceManager::UpdateFrontendDisplays() {