clk: Only enable the parent clock if the clock was enabled before reparenting

clk: Only enable the parent clock if the clock was enabled before reparenting

The current implementation of clk_set_parent() unconditionally enables
the new parent clock, even if the target clock was not previously enabled.

To avoid this implicit behavior, this patch adds a check for whether
the target clock has been enabled before parent enabling..

Fixes: ac30d90f336 ("clk: Ensure the parent clocks are enabled while reparenting")
Signed-off-by: Maksim Kiselev <bigunclemax@gmail.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>