drivers: usb_dc_stm32: enable VDDUSB on STM32L4x2
drivers: usb_dc_stm32: enable VDDUSB on STM32L4x2

The STM32L4x2 SoCs need to control the isolation of the USB features
from VDDUSB. This is done through the PWR_CR2 bit USV, however the
current code checks for the PWR_CR2_PVME1 bit instead, which is only
available on Cat. 3 devices. This bug is also present int the HAL and
likely copied from there.

Replace the check by PWR_CR2_USV instead.

Signed-off-by: Aurelien Jarno <bceb368e7f2cb351af47298f32034f0587bbe4a6@aurel32.net>

GiulianoFranchetto/zephyr,Vudentz/zephyr,mbolivar/zephyr,kraj/zephyr,explora26/zephyr,galak/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyriot/zephyr,kraj/zephyr,punitvara/zephyr,punitvara/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,zephyriot/zephyr,finikorg/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,kraj/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,explora26/zephyr,Vudentz/zephyr,mbolivar/zephyr,mbolivar/zephyr,Vudentz/zephyr,galak/zephyr,punitvara/zephyr,Vudentz/zephyr,punitvara/zephyr,explora26/zephyr,nashif/zephyr,zephyriot/zephyr,Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,explora26/zephyr,ldts/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,zephyriot/zephyr,finikorg/zephyr,zephyriot/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,ldts/zephyr,punitvara/zephyr,nashif/zephyr,nashif/zephyr,nashif/zephyr,explora26/zephyr,kraj/zephyr