Add support to output received reference clock. Model the received reference clock as an alternate parent of reference clock driver clock. When received refclk is selected to output on cmn_refclk_p/m, this is the internal reference clock driven on the pma_cmn_refclk_int. Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com> Link: https://lore.kernel.org/r/20210922123735.21927-5-sjakhade@cadence.com Signed-off-by: Vinod Koul <vkoul@kernel.org>