SF: Remove DisplayDevice::DisplayType conditionals

DisplayDevice::DisplayType will be removed in a follow-up CL.

Bug: 74619554
Test: Build
Change-Id: I215583ecc9594ce3707642bb840b479aae736c1f
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index b7fa6cb..952a63f 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -451,7 +451,7 @@
     }
 
     mOrientation = orientation;
-    if (mType == DisplayType::DISPLAY_PRIMARY) {
+    if (isPrimary()) {
         uint32_t transform = 0;
         switch (mOrientation) {
             case DisplayState::eOrientationDefault: