usb: usb_dc_native_posix: Fix buffer and max data 0 case
usb: usb_dc_native_posix: Fix buffer and max data 0 case

When both buffer and max data to read are zero return
the available data in buffer.

Fixes #20838

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

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