hwc2: Get Mapper instance in frame dump utility

Mapper instance is not available if frame dump is called prior to
buffer allocation through hwc buffer allocator.

Change-Id: I2b92aa594978d996be8f0036ac7c006fe23d3efa
CRs-Fixed: 2233209
diff --git a/sdm/libs/hwc2/hwc_buffer_allocator.cpp b/sdm/libs/hwc2/hwc_buffer_allocator.cpp
index 0ebd9a4..c879e94 100644
--- a/sdm/libs/hwc2/hwc_buffer_allocator.cpp
+++ b/sdm/libs/hwc2/hwc_buffer_allocator.cpp
@@ -400,6 +400,10 @@
 }
 
 DisplayError HWCBufferAllocator::MapBuffer(const private_handle_t *handle, int acquire_fence) {
+  auto err = GetGrallocInstance();
+  if (err != kErrorNone) {
+    return err;
+  }
   void *buffer_ptr = NULL;
   const IMapper::Rect access_region = {.left = 0, .top = 0, .width = 0, .height = 0};