drm_hwcomposer: Rename DrmProperty::immutable()

To be a little more precise, add an 'is_' prefix

Change-Id: Idd8fe45a4dfba1cd778b4ed6b761ec489697c31a
Signed-off-by: Sean Paul <seanpaul@chromium.org>
diff --git a/drmdisplaycompositor.cpp b/drmdisplaycompositor.cpp
index a1ccdc7..8599363 100644
--- a/drmdisplaycompositor.cpp
+++ b/drmdisplaycompositor.cpp
@@ -359,7 +359,8 @@
         }
       }
 
-      if (plane->zpos_property().id() && !plane->zpos_property().immutable()) {
+      if (plane->zpos_property().id() &&
+          !plane->zpos_property().is_immutable()) {
         ret = drmModeAtomicAddProperty(pset, plane->id(),
                                        plane->zpos_property().id(),
                                        source_layers.front()) < 0;
diff --git a/drmproperty.cpp b/drmproperty.cpp
index 9a28374..e276f56 100644
--- a/drmproperty.cpp
+++ b/drmproperty.cpp
@@ -95,7 +95,7 @@
   }
 }
 
-bool DrmProperty::immutable() const {
+bool DrmProperty::is_immutable() const {
   return id_ && (flags_ & DRM_MODE_PROP_IMMUTABLE);
 }
 
diff --git a/drmproperty.h b/drmproperty.h
index 36cd63d..5b40c4c 100644
--- a/drmproperty.h
+++ b/drmproperty.h
@@ -46,7 +46,7 @@
   std::string name() const;
 
   std::tuple<int, uint64_t> value() const;
-  bool immutable() const;
+  bool is_immutable() const;
 
  private:
   class DrmPropertyEnum {
diff --git a/platform.h b/platform.h
index a58d62e..6fdece2 100644
--- a/platform.h
+++ b/platform.h
@@ -90,7 +90,7 @@
         ret = ValidatePlane(plane, layer.second);
         if (!ret)
           break;
-        if (!plane->zpos_property().immutable())
+        if (!plane->zpos_property().is_immutable())
           unused_planes.push_back(plane);
         plane = PopPlane(planes);
       }