smdk5420: board: add functions required to enable USB DWC3

This commit adds implementation of function calls:
- usb_gadget_handle_interrupts()
- board_usb_init()

Which allow enable USB DWC3 gadget for this board.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Inha Song <ideal.song@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
2 files changed