twrp.cpp: Add guard for device without vendor_dlkm partiton

Change-Id: I17697dc7cf7b75d0cbefcacbd22f53741600a77c
diff --git a/twrp.cpp b/twrp.cpp
index c4b1b40..9c6882b 100644
--- a/twrp.cpp
+++ b/twrp.cpp
@@ -394,9 +394,12 @@
 
 #ifdef TW_LOAD_VENDOR_MODULES
 	if (startup.Get_Fastboot_Mode()) {
+		TWPartition* ven_dlkm = PartitionManager.Find_Partition_By_Path("/vendor_dlkm");
 		android::base::SetProperty("ro.boot.fastboot", "1");
 		PartitionManager.Prepare_Super_Volume(PartitionManager.Find_Partition_By_Path("/vendor"));
-		PartitionManager.Prepare_Super_Volume(PartitionManager.Find_Partition_By_Path("/vendor_dlkm"));
+		if(ven_dlkm) {
+			PartitionManager.Prepare_Super_Volume(ven_dlkm);
+		}
 	}
 	KernelModuleLoader::Load_Vendor_Modules();
 #endif