clk: ingenic: Make PLL clock enable_bit and stable_bit optional

When the enable bit is undefined, the clock is assumed to be always
on and enable/disable is a no-op. When the stable bit is undefined,
the PLL stable check is a no-op.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20221026194345.243007-3-aidanmacdonald.0x0@gmail.com


Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>