drivers: usb: stm32: Configure domain clock using device tree

This change doesn't consider STM32F1 series.

There are 5 categories of STM32 regarding USB domain clock:
A] USB domain clocks directly driven by CK48 clocks
B] USB domain clocks which can select either CK48 or an alternative clock
C] USB domain clocks which can select between MSI or PLL
D] USB domain clocks relying statically on a PLL output
E] USB domain clocks which can be set on 2 different PLL ouputs

For case A], there is nothing to be done. Clk48 was already configured
in a previous change (51c7643295b02ba26ddcd0fd915484114db7101c).
For case B] and C] USB domain clocks will need to be configured in
each board.
For case D] and E] relying on existing dts configuration. Though
there is no easy build time chekc that can be done.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>