ARM: tegra: select USB_ULPI from EHCI rather than platform

For historic reasons, the tegra platform selects USB_ULPI from architecture
code, but that hasn't really made sense for a long time, as the only
user of that code is the Tegra EHCI driver that has its own Kconfig
symbol.

This removes the 'select' statements from mach-tegra and drivers/soc/tegra
and adds them with the device driver that actually needs them.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>