usb-ccid: add CCID bus

A CCID device is a smart card reader. It is a USB device, defined at [1].
This patch introduces the usb-ccid device that is a ccid bus. Next patches will
introduce two card types to use it, a passthru card and an emulated card.

 [1] http://www.usb.org/developers/devclass_docs/DWG_Smart-Card_CCID_Rev110.

Signed-off-by: Alon Levy <alevy@redhat.com>

---

changes from v20->v21: (Jes Sorenson review)
 * cosmetic changes - fix multi line comments.
 * reorder fields in USBCCIDState
 * add reference to COPYING
 * add --enable-smartcard and --disable-smartcard here (moved
 from last patch)

changes from v19->v20:
 * checkpatch.pl

changes from v18->v19:
 * merged: ccid.h: add copyright, fix define and remove non C89 comments
 * add qdev.desc

changes from v15->v16:

Behavioral changes:
 * fix abort on client answer after card remove
 * enable migration
 * remove side affect code from asserts
 * return consistent self-powered state
 * mask out reserved bits in ccid_set_parameters
 * add missing abRFU in SetParameters (no affect on linux guest)

whitefixes / comments / consts defines:
 * remove stale comment
 * remove ccid_print_pending_answers if no DEBUG_CCID
 * replace printf's with DPRINTF, remove DEBUG_CCID, add verbosity defines
 * use error_report
 * update copyright (most of the code is not original)
 * reword known bug comment
 * add missing closing quote in comment
 * add missing whitespace on one line
 * s/CCID_SetParameter/CCID_SetParameters/
 * add comments
 * use define for max packet size

Comment for "return consistent self-powered state":

the Configuration Descriptor bmAttributes claims we are self powered,
but we were returning not self powered to USB_REQ_GET_STATUS control message.

In practice, this message is not sent by a linux 2.6.35.10-74.fc14.x86_64
guest (not tested on other guests), unless you issue lsusb -v as root (for
example).
