usb: board_usb_init and board_usb_cleanup calls in the fastboot command

usb: board_usb_init and board_usb_cleanup calls in the fastboot command

Each USB download function command calls board_usb_init before registering the
USB gadget and board_usb_cleanup after de-registering it. On devices currently
using fasboot, musb-new is usually initialized earlier, but some other boards
might need the board_usb_init call to properly initialize musb-new.

This requires adding an argument (the USB controller index) to the fastboot
command, as it is currently done with other USB download gadget functions.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>
Test HW: Odroid_XU3 (Exynos5422), trats (Exynos4210)