phy: cdns-dphy: Store hs_clk_rate and return it

phy: cdns-dphy: Store hs_clk_rate and return it

The DPHY driver does not return the actual hs_clk_rate, so the DSI
driver has no idea what clock was actually achieved. Set the realized
hs_clk_rate to the opts struct, so that the DSI driver gets it back.

Reviewed-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Tested-by: Parth Pancholi <parth.pancholi@toradex.com>
Tested-by: Jayesh Choudhary <j-choudhary@ti.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20250723-cdns-dphy-hs-clk-rate-fix-v1-1-d4539d44cbe7@ideasonboard.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>