Remove dangling ptr in rsdAllocationInit

Possible dangling ptr in exceptional case.

Change-Id: I4f5353b7709b215d4d79748c60668fdfadaf048f
diff --git a/driver/rsdAllocation.cpp b/driver/rsdAllocation.cpp
index 8956b2e..5475041 100644
--- a/driver/rsdAllocation.cpp
+++ b/driver/rsdAllocation.cpp
@@ -294,6 +294,7 @@
 
         ptr = (uint8_t *)malloc(allocSize);
         if (!ptr) {
+            alloc->mHal.drv = NULL;
             free(drv);
             return false;
         }