Codec2: fix leaked graphic buffer handles

Unmap the locked handles when returning from error conditions

b/221226088

Test:
  android.media.cts.ImageReaderDecoderTest#testOtherH265_10BitImage

Change-Id: I7f3dd968a856fb66c15e172131a2357f4a99cd42
diff --git a/media/codec2/vndk/C2AllocatorGralloc.cpp b/media/codec2/vndk/C2AllocatorGralloc.cpp
index b5200a5..d8d6f06 100644
--- a/media/codec2/vndk/C2AllocatorGralloc.cpp
+++ b/media/codec2/vndk/C2AllocatorGralloc.cpp
@@ -265,6 +265,7 @@
 
         for (const PlaneLayoutComponent &component : plane.components) {
             if (!gralloc4::isStandardPlaneLayoutComponentType(component.type)) {
+                mapper.unlock(handle);
                 return C2_CANNOT_DO;
             }
 
@@ -287,6 +288,7 @@
                     channel = C2PlaneInfo::CHANNEL_CR;
                     break;
                 default:
+                    mapper.unlock(handle);
                     return C2_CORRUPTED;
             }