staging: comedi: ni_pcidio: use request_firmware()

The PCI-6534 needs three firmware files loading to work with the driver.
That is currently done by passing the firmware data using the
`COMEDI_DEVCONFIG` ioctl that uses the comedi `attach()` hook in the
driver.  This doesn't work for auto-configured PCI devices (which also
currently use the `attach()` hook in this driver, but doesn't have the
firmware-loading options set in the `struct comedi_devconfig *`
parameter).

Change the driver to request the firmware files using
`request_firmware()`, ignoring any firmware-loading options set in the
`struct comedi_devconfig`.

The PCI-6534 has a main FPGA which needs to be loaded first, and two
"scarabs".  Scarab A is loaded with firmware to support digital input
mode, and scarab B is loaded with firmware to support digital output
mode.

I don't think the order of loading the scarab firmwares matters as long
as they are loaded with the correct firmware files.  This update loads
scarab B first, whereas the original code loaded scarab A first.  The
firmware files are loaded in the following order:

A) main FPGA: "ni6534a.bin" (FW_PCI_6534_MAIN)
B) scarab B: "niscrb02.bin" (FW_PCI_6534_SCARAB_DO)
C) scarab A: "niscrb01.bin" (FW_PCI_6534_SCARAB_DI)

The required firmware files can be found in the
"comedi-nonfree-firmware" tar-ball at
<http://www.comedi.org/download/comedi-nonfree-firmware-2007.06.22.tar.gz

>.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>