ipq806x: Add USB support

This patch adds code to initialize the two DWC3 USB host controllers and
their associated PHYs to the IPQ806x SoC (closely imitating the existing
DWC3 implementation for Exynos5), and uses them to initialize USB on the
Storm mainboard.

TEST=Hack up netboot to get around missing SPI flash, load a file over
TFTP. Hack a storage read into the storage attach function, dump the
data and confirm that it looks right. Enable USB debugging and confirm
3.0 devices get enumerated at SuperSpeed (mostly).

Original-Change-Id: Iaf7b96bef994081ca222b7de9d8e8c49751d3f1d
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202157
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Original-Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
(cherry picked from commit 6349e7281d5accb1247acb0537a48fa3a5e1bf97)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I749d265d45c6a807a7559bd4df2490a6eb8067af
Reviewed-on: http://review.coreboot.org/8056
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
8 files changed