dmaengine: rcar-dmac: Update copyright information

Update copyright and string for Gen3.

Signed-off-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vkoul@kernel.org>