gpu: mali: get rid of kbase_page_metadata

Use the lru list_head in the page struct to avoid having to allocate
a struct just to hold the list_head and page pointer.  Also avoids
storing the list_head inside the page for lowmem pages, removing a
cache flush on allocation.

Change-Id: I3400f3109c8839502debb50a754308449bf28f52
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>