arm64: Support early fixup for CMA

Although it isn't architecturally required, CMA regions may need
to have attributes changed at runtime. Remap the CMA regions as
pages to allow this to happen.

Change-Id: I7dd7fa150ce69fdf05f8bf6f76a5ae26dd67ff1b
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>