phy: sparx5-serdes: add skip_cmu_cfg check when configuring lanes

phy: sparx5-serdes: add skip_cmu_cfg check when configuring lanes

Add a check for skip_cmu_cfg when configuring the serdes lane.  All
individual serdeses are reset upon first configuration. Resetting the
serdes involves reconfiguring it with preset values. The serdesmode is
required to determine the clock-providing CMU, therefore make sure the
serdes is not reconfigured if the serdesmode is not set.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://lore.kernel.org/r/20230417180335.2787494-8-daniel.machon@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>