hwc2: Remove Display::{mIsVirtual,setVirtual}

Trivial cleanup.

Now that mType is available, we don't need a separate flag for whether
the display is virtual. The remaining effect of setVirtual was to set
the display connected, so just use setConnected.

Bug: b/36597125
Test: build
Change-Id: Ia1fa4a324cc07b0d6c124f4f50966c8b0cbe4827
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.cpp b/services/surfaceflinger/DisplayHardware/HWC2.cpp
index 402009a..62c5aff 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2.cpp
@@ -244,7 +244,7 @@
         ALOGE("Failed to get display by id");
         return Error::BadDisplay;
     }
-    (*outDisplay)->setVirtual();
+    (*outDisplay)->setConnected(true);
     return Error::None;
 }
 
@@ -531,7 +531,6 @@
   : mDevice(device),
     mId(id),
     mIsConnected(false),
-    mIsVirtual(false),
     mType(DisplayType::Invalid)
 {
     ALOGV("Created display %" PRIu64, id);
@@ -553,7 +552,7 @@
 Display::~Display()
 {
     ALOGV("Destroyed display %" PRIu64, mId);
-    if (mIsVirtual) {
+    if (mType == DisplayType::Virtual) {
         mDevice.destroyVirtualDisplay(mId);
     }
 }