Staging: poch: Fetch Flush IOCTL interface

Change user space interface to an IOCTL based interface instead of a
memory mapped circular buffer. The circular buffer had some serious
cache(?) issues and never worked.

Signed-off-by: Vijay Kumar B. <vijaykumar@bravegnu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>