linux-wandboard

MLK-16416-1 clk: imx: scu mux: refactor set/get_parent method

The current clk_mux_set_parent_scu() implementation returns error
if device power domain is not enabled. As consequence of this the
existing "assigned-clock-parents" DTS functionality cannot be used for
clk_mux. In order to avoid returning error in "set_parent" the code is
refactored as follows:

a) On "set_parent" the "mux->reg" value is prepared and stored in
   "mux->val" field. The "mux->reg" is updated if power domain is enabled,
   or triggered for update on "prepare" subsequent call otherwise.

b) On "prepare" the power domain status check is performed and "mux->val"
   is stored in "mux->reg" if triggered for update.

c) On "get_parent" the "mux->reg" is not read anymore and "mux->val" is
   used to get the "get_parent" output.

Signed-off-by: Viorel Suman <viorel.suman@nxp.com>
Reviewed-by: Ranjani Vaidyanathan <ranjani.vaidyanathan@nxp.com>