ANDROID: arm64: dts: hikey960: Add CMA entry for ION/framebuffers

Add CMA entry, as the DRM driver requires phys contig
memory for framebuffers. These are normally allocated
out of ION by gralloc for the graphics framebuffer.

NOTE: On the 4gb boards, if we don't specify the address,
the cma region we use for the framebuffer and ion heap
may be placed in memory mapped above 32bits.

Due to addresses being masked to 32bits for DMA, this
resulted in crashes on newer 4gb boards.

Thus this patch forces CMA address to be lower in memory.

I've picked an address just past a previous CMA reserved
chunk, so we shouldn't be adding to any fragmentation.

Extra thanks to Ryan Grachek <ryan@edited.us> who
helped isolate the issue with the CMA buffers being over
the 32bit barrier.

Bug: 146450171
Change-Id: Ibb7ff1d85a9b93e41c440ffacf6a1ccf6aecb1ca
Signed-off-by: John Stultz <john.stultz@linaro.org>