usb: increase the length of the request buffer
usb: increase the length of the request buffer

Increase the length of the request buffer.
Current value is not enough for an average
device descriptor.

Signed-off-by: Johann Fischer <b39b26e1812eb092eb217277792f3735321fa456@phytec.de>

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