The existing implementation for doing DMA via asynchronous IO didn't
work and there was no longer a use-case for it.  Removed it.

Fixed a few checkpatch warnings about too-long lines and extraneous
braces in the process.

Reported-by: Matt Sickler <matt.sickler@daktronics.com>
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>