Remove ndk_platform backend. Use the ndk backend.

The ndk_platform backend will soon be deprecated because the ndk backend
can serve the same purpose. This is to eliminate the confusion about
having two variants (ndk and ndk_platform) for the same ndk backend.

Bug: 161456198
Test: m
Change-Id: I1e84945fcfef3b2a300811f27ef57059eaf08553
diff --git a/libs/ui/Android.bp b/libs/ui/Android.bp
index 5a118ec..ba5a64f 100644
--- a/libs/ui/Android.bp
+++ b/libs/ui/Android.bp
@@ -158,7 +158,7 @@
         "android.hardware.graphics.allocator@2.0",
         "android.hardware.graphics.allocator@3.0",
         "android.hardware.graphics.allocator@4.0",
-        "android.hardware.graphics.common-V2-ndk_platform",
+        "android.hardware.graphics.common-V2-ndk",
         "android.hardware.graphics.common@1.2",
         "android.hardware.graphics.mapper@2.0",
         "android.hardware.graphics.mapper@2.1",
@@ -175,7 +175,7 @@
 
     export_shared_lib_headers: [
         "android.hardware.graphics.common@1.2",
-        "android.hardware.graphics.common-V2-ndk_platform",
+        "android.hardware.graphics.common-V2-ndk",
         "android.hardware.graphics.mapper@4.0",
         "libgralloctypes",
     ],