usb: stm32: add usb_dc_ep_read_wait/conitinue
usb: stm32: add usb_dc_ep_read_wait/conitinue

usb mass example need usb_dc_ep_read_wait/continue API.
test usb mass storage with RAM DISK on stm32f4 series.

Signed-off-by: qianfan Zhao <0d01fab1932da5a147025f14dd5829cf5bf10d4d@163.com>

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