ext/hal/stm32l0xx: Remove stm32l0xx_ll_usb from CMakeLists
ext/hal/stm32l0xx: Remove stm32l0xx_ll_usb from CMakeLists

STM32Cube doesn't provide a USB LL API for STM32L0XX series.
This patch removes stm32l0xx_ll_usb.c from CMakeLists because
it doesn't exist.

Signed-off-by: Yannis Damigos <bda985a2727ac24c41652a294292988d6fc7dc73@gmail.com>

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