Staging: add poch driver

This is the first cut at a driver for the Redrapids Pocket Change
CardBus devices.

Receiving data seems to work properly, but overflows happen on transmit.
Still needs more hardware debugging to work properly.

(cleaned up to use proper driver core api functions by Greg)

From: Vijay Kumar <vijaykumar@bravegnu.org>
Cc: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Cc: Jaya Kumar <jayakumar.lkml@gmail.com>
Cc: Ken Sienski <sienski@redrapids.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>