DrmHalTest: null check for skipped test

Bug: 253168737
Change-Id: I0dea0d2482d607eecff433ffb901eba02a39770f
Test: VtsAidlHalDrmTargetTest
diff --git a/drm/aidl/vts/drm_hal_common.cpp b/drm/aidl/vts/drm_hal_common.cpp
index f5ef0e7..f0445a5 100644
--- a/drm/aidl/vts/drm_hal_common.cpp
+++ b/drm/aidl/vts/drm_hal_common.cpp
@@ -263,6 +263,9 @@
 }
 
 bool DrmHalTest::isCryptoSchemeSupported(Uuid uuid, SecurityLevel level, std::string mime) {
+    if (drmFactory == nullptr) {
+        return false;
+    }
     CryptoSchemes schemes{};
     auto ret = drmFactory->getSupportedCryptoSchemes(&schemes);
     EXPECT_OK(ret);