rockchip/rk3399: Add code to neuter Type-C PHY for firmware USB

The Rockchip RK3399 integrates a USB Type-C PHY in charge of things like
SuperSpeed line muxing for rotated cable orientations in the SoC. While
fancy, this is very complicated and we don't want to implement support
for the whole thing in firmware. The USB Type-C standard has
intentionally been designed in a way that the USB 2.0 (HighSpeed) lines
always "just work" in any orientation (by just shorting different pins
in the connector together) so that simple use cases like ours can get
basic USB functionality without much hassle.

However, a semi-configured Type-C PHY can confuse USB 3.0 capable
devices into thinking we're actually supporting SuperSpeed, and fail at
that rather than establishing a reliable HighSpeed connection. This
patch sets enough bits in the Type-C PHY to electrically isolate the
SuperSpeed lines from the connector so that the connected device isn't
going to get any fancy ideas and reliably falls back to USB 2.0.

Also clean up the rest of the USB code while we're at it: avoid writing
a few bits that are already in the right state from their reset values
anyway, or reading values whose content we already know for this SoC.
Rename the USB controllers to the name actually used in the Rockchip
documentation (USB OTGx) rather than the name blindly copied from
Exynos code (USB DRDx).

BRANCH=None
BUG=chrome-os-partner:54621
TEST=Plug a USB 3.0 Patriot Memory stick into both ports in all
orientations, observe how it gets reliably detected now (safe for some
known hardware issues on my board).

Change-Id: Ifce6bcddd69f2e8f2e2a2f48faf65551e084da1e
Signed-off-by: Martin Roth <martinroth@chromium.org>
Original-Commit-Id: c526906f998bf66067d3addb8b3d3a126c188b1e
Original-Change-Id: Ie80a201a58764c4d851fe4a5098a5acfc4bcebdf
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/366160
Original-Reviewed-by: liangfeng wu <wulf@rock-chips.com>
Original-Reviewed-by: Shelley Chen <shchen@chromium.org>
Original-Reviewed-by: <515506667@qq.com>
Reviewed-on: https://review.coreboot.org/16125
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

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