phy: cadence-torrent: Do not configure SERDES if it's already configured

Do not configure torrent SERDES if it's already configured.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Swapnil Jakhade <sjakhade@cadence.com>
Link: https://lore.kernel.org/r/20210330110138.24356-4-kishon@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>