ARM: dts: msm: Add ion heaps for sdm640

Add device tree configuration corresponding to all supported
ion heaps to allow clients to allocate memory from ion for
sdm640.

Change-Id: I820e063e42e0c2b4246564c92e20916a2dfa2b74
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>