dt-bindings: clock: renesas: Convert to SPDX identifiers

This patch updates license to use SPDX-License-Identifier
instead of verbose license text on Renesas related headers.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

clk: renesas: Add r8a7793 CPG Core Clock Definitions

Add all R-Car M2-N Clock Pulse Generator Core Clock Outputs, as listed
in Table 7.2b ("List of Clocks [R-Car M2-W/M2-N]") of the R-Car Gen2
Hardware User's Manual rev. 2.00.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>