drm_hwcomposer: add a .clang-format for our style

Change-Id: If6059a0456376d2aba6ad09af28fbb7add33f0b4
(cherry picked from commit fd425aec49615e749e1edc596384a3502ea0db05)
diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..5382f9b
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,4 @@
+BasedOnStyle: Google
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None