display: Remove C++ standard flags

Some headers included by display modules require c++17 now in newer
builds. Remove the forced standard setting to let the build pick
the latest C++ version

Change-Id: I76f9e0c03ce08100c3dd7caf5932eaa941fff0c8
diff --git a/sdm/libs/hwc2/Android.mk b/sdm/libs/hwc2/Android.mk
index 042b9cd..0ec89da 100644
--- a/sdm/libs/hwc2/Android.mk
+++ b/sdm/libs/hwc2/Android.mk
@@ -14,7 +14,7 @@
 LOCAL_HEADER_LIBRARIES        := display_headers
 
 LOCAL_CFLAGS                  := -Wno-missing-field-initializers -Wno-unused-parameter \
-                                 -std=c++11 -fcolor-diagnostics\
+                                 -fcolor-diagnostics\
                                  -DLOG_TAG=\"SDM\" $(common_flags)
 LOCAL_CLANG                   := true