CHERRY-PICK: CHROMIUM: Bluetooth: Add intel_btusb module for Intel Bluetooth device

Intel Bluetooth device (7260) requires device firmware patching before
the host send HCI initialization commands. This setup routine was added
in 3.10 kernel with a framework support from the Bluetooth subsystem
which is also introduced in 3.10 kernel.

Because the backporting this setup routine from 3.10 to 3.8 requires
also backporting Bluetooth framework change, which is significant in
the Bluetooth subsystem, it is not recommened by the Google maintainer.

Thus, intel_btusb module is forked from btusb module to have its own
device firmware setup routine without changing Bluetooth susbsystem.

Even if it is for Intel Bluetooth device, any other routines such as
submit USB urb, interrupt handling, and ISOC setup are same as btusb
module.

This is a custom patch for ChromeOS

BUG=chrome-os-partner:21770
TEST=tested with HID mouse and A2DP headset

Reviewed-on: https://chromium-review.googlesource.com/190552
Reviewed-by: Scott James Remnant <keybuk@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Commit-Queue: Tedd An <tedd.an@intel.com>
Tested-by: Tedd An <tedd.an@intel.com>

(cherry picked from commit 79bb09871087d3b44f4cf302a529115db4150d38)

Change-Id: Icfc99c1abf661fcb3067049c5c1842723f8ae605
Reviewed-on: https://chromium-review.googlesource.com/193161
Reviewed-by: Scott James Remnant <keybuk@chromium.org>
Commit-Queue: Jay Kim <yongjaek@chromium.org>
Tested-by: Jay Kim <yongjaek@chromium.org>