ARM: dts: r8a7794: Update CMT compat strings

Use recently updated R-Car Gen2 CMT0 and CMT1 compat strings.

With this change in place we can keep device-specific configuration in
the driver and the driver can be able to support CMT1 specific features.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>