clk: ingenic: Read bypass register only when there is one

Rework the clock code so that the bypass register is only read when
there is actually a bypass functionality.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210530164923.18134-4-paul@crapouillou.net
Tested-by: 周琰杰 (Zhou Yanjie)<zhouyanjie@wanyeetech.com> # on CU1830-neo/X1830
Signed-off-by: Stephen Boyd <sboyd@kernel.org>