ANDROID: GKI: Enable CONFIG_USB_MON=m

Enable CONFIG_USB_MON to help with debugging USB related issues.

This module reports requests made by peripheral-specific drivers to
Host Controller Drivers (HCD). The data reported can be examined by a
userspace tool.

Enable as a loadable module so that vendors can choose whether or not
to package this in their builds.

Bug: 335775484
Change-Id: I4613064229adc1e7de6ddcc20208d9f28d265cf9
Signed-off-by: Khoa Hong <khoahong@google.com>