firewire: ohci: Turn remote DMA support into a module parameter

This makes it possible to debug kernel over FireWire without the need to
recompile it.

[Stefan R: changed description from "...0" to "...N"]

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --cc Documentation/debugging-via-ohci1394.txt
Simple merge

diff --cc drivers/firewire/ohci.c
Simple merge

diff --cc lib/Kconfig.debug
Simple merge