phy: cadence-torrent: Add support to output received reference clock

phy: cadence-torrent: Add support to output received reference clock

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>