clk: sunxi-ng: replace lib-y with obj-y

We had commit 06e226c7fb23 ("clk: sunxi-ng: Move all clock types to a
library") and commit 799c43415442 ("kbuild: thin archives make default
for all archs") in the same development cycle, from different trees.

With migration to the thin archive, the entire drivers/clk/sunxi-ng/lib.a
is linked to the vmlinux.  This does not break build, but we do not get
any size saving.

However, we do not need to go back to the individual Kconfig options.
The default configuration pulls in all (or most) of the CCU parts anyway.
Also, once we enable CONFIG_LD_DEAD_CODE_DATA_ELIMINATION, we can simply
list all files with obj-y, and the linker will drop all unused functions
by itself.

After the long discussion [1], people there agreed to fix this, but
nobody sent a patch after all.  I am doing it now.

I lifted up CONFIG_SUNXI_CCU to drivers/clk/Makefile because everything
in drivers/clk/sunxi-ng/ depends on SUNXI_CCU.

[1] https://patchwork.kernel.org/patch/9796521/



Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>