phy: cadence-torrent: Add single link PCIe support

commit 3a333a188e1f7a5f30e9e037d7f332383ac454ae from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git

Add single link PCIe register sequences in Torrent PHY driver.
Also, add support for getting SSC type from DT.

Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>