Marvell/Library: UtmiLib: Fix USB mux configuration

If UTMI connected to USB Device, the MUX must be configured
prior to the PHY init. Add missing register update in the
relevant code.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>