MIPS, clk: move jz4740 clock suspend, resume functions to jz4740-cgu

MIPS, clk: move jz4740 clock suspend, resume functions to jz4740-cgu

The jz4740-cgu driver already has access to the CGU, so it makes sense
to move the few remaining accesses to the CGU from arch/mips/jz4740
there too. Move the jz4740_clock_{suspend,resume} functions there for
such consistency. The arch/mips/jz4740/clock.c file now contains nothing
more of use & so is removed.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
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: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10158/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>