exynos5: Refactor board-specific parts out of USB PHY code

This patch moves around some of the existing Exynos5 USB 2.0 PHY code
to make it cleaner in preparation of the 3.0 PHYs. It moves the VBUS
GPIOs (which are completely board-specific) into the mainboard code and
makes sure to only initialize PHYs on the boards that actually need
them. It also removes the USB 3.0 PLL hack that was needed on Snow from
the Pit and Kirby boards (which do not have that PLL anymore).

BUG=chrome-os-partner:21969
TEST=Manual

Change-Id: Ia35f47a765acff60481f0907f7448ec4f78e0937
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/66887
Reviewed-by: Stefan Reinauer <reinauer@google.com>
18 files changed