Use ro.board.api_level instead of ro.vndk.version

VNDK's getting deprecated so ro.board.api_level is the right sysprop to
use for vendor api version.

Bug: 311267616
Test: builds
Change-Id: Ie73bef793cd811d16b9b781b2bf38d9a52558547
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 0c0639e..4c2da91 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -3635,7 +3635,7 @@
             // to upsert RenderEngine's caches. Put in a special workaround to be backwards
             // compatible with old vendors, with a ticking clock.
             static const int32_t kVendorVersion =
-                    base::GetIntProperty("ro.vndk.version", __ANDROID_API_FUTURE__);
+                    base::GetIntProperty("ro.board.api_level", __ANDROID_API_FUTURE__);
             if (const auto format =
                         static_cast<aidl::android::hardware::graphics::common::PixelFormat>(
                                 mBufferInfo.mBuffer->getPixelFormat());