gpu: ion: Add more debug info

Add more debug information to ion_debug_heap_show:
-Get number of allocations from heap
-Get number of user space mappings.
-Get number of kernel space mappings.
-Get indicator whether heaps has been secured or not.

Change-Id: I05491b3dd8caccfc3bbe5a9e55642e5e2cd431c4
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>