usb: usb_dc_stm32: Add missing function
usb: usb_dc_stm32: Add missing function

Add missing API functions which will be tested with harness tests.

Signed-off-by: Andrei Emeltchenko <a6565233ddc88e4fb9c66c1d70743223493f2ed4@intel.com>

ldts/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,ldts/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr