aoc: usb: Add USB control commands and XHCI hooks

- Add USB control commands for setting up the device context on AoC.
- Add XHCI hooks implementation.
- Cleanup the code.

Bug: 167651956
Test: build and boot pass
Signed-off-by: Howard Yen <howardyen@google.com>
Change-Id: I6bb1f1bcf2e0b1298a732eaadf95acc2eaf7e964