ARM: shmobile: r8a7791: Add JPU device node.

This patch contains device tree node definition for JPEG codec peripheral
found in the Renesas R-Car r8a7791 SoC.

Signed-off-by: Mikhail Ulyanov <mikhail.ulyanov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>