phy: qcom: Introduce new eDP PHY driver

Many recent Qualcomm platforms comes with native DP and eDP support.
This consists of a controller in the MDSS and a QMP-like PHY.

While similar to the well known QMP block, the eDP PHY only has TX lanes
and the programming sequences are slightly different. Rather than
continuing the trend of parameterize the QMP driver to pieces, this
introduces the support as a new driver.

The registration of link and pixel clocks are borrowed from the QMP
driver. The non-DP link frequencies are omitted for now.

The eDP PHY is very similar to the dedicated (non-USB) DP PHY, but only
the prior is supported for now.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20211103234410.1352424-2-bjorn.andersson@linaro.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>