clk: ingenic: add JZ4780 CGU support

clk: ingenic: add JZ4780 CGU support

Add support for the clocks provided by the CGU in the Ingenic JZ4780
SoC, making use of the SoC-agnostic CGU code to do the heavy lifting.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Co-authored-by: Paul Cercueil <paul@crapouillou.net>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: linux-clk@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10157/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>