Netfs: Fix memory error

In Reader::Read(), memory is allocated to '*buffer' at line 40,
but freed with 'buffer' at line 45.
Pointed by Clang Static Analyzer.

Change-Id: I18e49791da639a6bc2041e944a39ceb73a2e5055
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1931
Reviewed-by: Axel Dörfler <axeld@pinc-software.de>

src/add-ons/kernel/file_systems/netfs/shared/RequestUnflattener.cpp

@@ -42,7 +42,7 @@ Reader::Read(int32 size, void** buffer, bool* mustFree)
 		return B_NO_MEMORY;
 	status_t error = Read(*buffer, size);
 	if (error != B_OK) {
-		free(buffer);
+		free(*buffer);
 		return error;
 	}
 	return error;