usb: bt_h4: Set stack sizes using Kconfig
usb: bt_h4: Set stack sizes using Kconfig

The previously used stack sizes where in many cases too small.

Signed-off-by: Rubin Gerritsen <eddef76671ab7f54bc92622aa9c9d13467ed93c1@nordicsemi.no>

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