msm: sde: remove ion usage in sde rotator

ion_alloc support is deprecated, so all internal buffers allocation
in sde rotator that use dmabuf need to maintain its own dmabuf
implementation. Current dmabuf implementation is only for supporting a
small 4Kb single page memory block, which is only used for sw timestamp
support. This patch also make changes to secure camera buffer mapping
which align to ion allocation providing dmabuf fd directly, and there
is no need to perform ion handle import.

Change-Id: Ic7f7090e2d2a93645ad09263ffa66b55f5853c22
Signed-off-by: Benjamin Chan <bkchan@codeaurora.org>