phy: qualcomm: qmp-combo: Add preliminary USB4 support

Some Combo PHYs (so far only on SC8280XP, X1E80100 and Glymur), come in
a flavor called USB43DP, which as the name implies, features USB4, USB3
and DP signal processing capabilities. In that architecture, USB3 and
USB4 PHYs share the same USB_PLL while featuring separate logic spaces.
The DP part is roughly the same as on the instances without USB4.

The USB4 and USB3/DP operation modes of the PHY are mutually exclusive.
Only one USB protocol (and flavor of pipe clock) can be active at a
given moment (not to be confused with USB3 not being able to be
tunneled as USB4 packets - that of course remains possible).
The DP PLL is still used for clocking tunneled DP links. It may be
turned off to save power when no tunnels are active, but that's left as
a TODO item for now.

Due to the nature of USB4, the Type-C handling happens entirely inside
the Host Router, and as such the QMPPHY's mux_set() function is
nullified for the period when USB4 PHY remains active. This is strictly
necessary, as the Host Router driver is going to exercise manual
control over the USB4 PHY's power state, which is needed by the suspend
and resume flows. Failure to control that synchronously with other
parts of the code results in a SoC crash by unlocked access.

Because of that, a new struct phy is spawned to expose the USB4 mode,
along with a .set_mode callback to allow toggling between USB4 and TBT3
submodes.

Thunderbolt 3, having a number of differences vs USB4, requires a
couple specific overrides, pertaining to electrical characteristics,
which are easily accommodated for.

Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260908-topic-usb4phy-v5-3-73aac69578ef@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

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