memshare: Change the compatible property field for child node

The compatible field for the child node is not strictly following
the documentation guidelines. This patch corrects the compatible
property value for child nodes for 8916 and 8939. It also enables
memshare driver for 8909.

Change-Id: I6c59acc752b4744fba1a866d71e07a2c32f9d90f
Signed-off-by: Katish Paran <kparan@codeaurora.org>