clk: Ingenic: Remove unnecessary spinlock when reading registers.

It is not necessary to use spinlock when reading registers,
so remove it from cgu.c.

Suggested-by: Paul Cercueil <paul@crapouillou.net>
Suggested-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lkml.kernel.org/r/20200528031549.13846-2-zhouyanjie@wanyeetech.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>