ARM: STi: DT: STiH410: Add usb2 picophy dt nodes

This patch adds the dt nodes for the extra usb2 picophys found on
the stih410.

These two picophys are used in conjunction with the extra ehci/ohci usb
controllers also found on the stih410 SoC.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>