gralloc: Conditionally revert changes related to gralloc struct

Revert this commit if gralloc struct does not have reserved_size field.

This conditionally reverts: "gralloc: Fix issue with mmap/munmap meta
due to reserved size", which relies on changes to the gralloc struct
in commit 34fef9c4f6e22d97c52ff60ccd93fc404ea6a4cb.

Change-Id: I7cfae76bfe8c999f4bbf3e03f2362b3c0e21e46d
2 files changed