ARM: shmobile: r8a7778: Add TMU nodes

This describes all of the TMU hardware of the r8a7778.
Each node is disabled and may be enabled as necessary
by board DTS files.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>