gpu: ion: Refactor common mapping functions out of system heap

The system heap contained several general purpose functions to map
buffers to the kernel and userspace.  This patch refactors those
into ion_heap.c so they can be used by other heaps.

Change-Id: If64591798bdc2c248bf9064ace2c927909d7adb8
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
gpu: ion: Add chunk heap

This patch adds support for a chunk heap that allows for buffers that are
made up of a list of fixed size chunks taken from a carveout.  Chunk sizes
are configured when the heaps are created by passing the chunk size in the
priv field of the heap platform data.

Change-Id: Ia9e003f727b553a92804264debe119dcf78b14e0
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
gpu: ion: Clarify variable names and comments around heap ids v types

There is some confusion between when to use the heap type and when
the id.  This patch clarifies this by using clearer variable names
and describing the intention in the comments.  Also fixes the client
debug code to print heaps by id instead of type.

Change-Id: Ie8b3dadded52e18590fcb2ca94001f6ed46ef07d
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
gpu: ion: Remove heapmask from client

The heapmask in the client generally wasn't being used.  This
patch removes it.

Change-Id: I3526723fbf8f2e81c28c0733deb583ea14bdd837
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>