phy: cadence-torrent: Add function to get PLL to be configured for DP

phy: cadence-torrent: Add function to get PLL to be configured for DP

Torrent PHY PLL0 or PLL1 is used for DP depending on the single link or
multilink protocol configuration for which PHY is configured. In multilink
configurations with other protocols, either PLL0 or PLL1 will be used
for DP. For single link DP, both PLLs need to be configured at POR.

Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com>
Link: https://lore.kernel.org/r/20230418173157.25607-2-sjakhade@cadence.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>