phy: hdmi: Add HDMI 2.1 FRL configuration options

phy: hdmi: Add HDMI 2.1 FRL configuration options

The HDMI 2.1 specification introduced the Fixed Rate Link (FRL) mode,
aiming to replace the older Transition-Minimized Differential Signaling
(TMDS) mode used in previous HDMI versions to support much higher
bandwidths (up to 48 Gbps) for modern video and audio formats.

FRL has been designed to support ultra high resolution formats at high
refresh rates like 8K@60Hz or 4K@120Hz, and eliminates the need for
dynamic bandwidth adjustments, which reduces latency.  It operates with
3 or 4 lanes at different link rates: 3Gbps, 6Gbps, 8Gbps, 10Gbps or
12Gbps.

Add support for configuring the FRL mode for HDMI PHYs.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://patch.msgid.link/20260113-phy-hdptx-frl-v6-1-8d5f97419c0b@collabora.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>