Add the compatible strings for the USB3 PHYs found on SM8150, SM8250
and SM8350 SoCs. These require separate subschemas due to the different
required clock entries.

Note the SM8150 and SM8250 compatibles have already been in place in
the dts as well as the driver implementation but were missing from
the documentation.
Signed-off-by: NJack Pham <jackp@codeaurora.org>
Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210115174723.7424-2-jackp@codeaurora.orgSigned-off-by: NVinod Koul <vkoul@kernel.org>