Sverker Wiberg <sverkerw@swipnet.se>

Sverker Wiberg <sverkerw@swipnet.se>

Opening the patch ROM on GusPnP always fails:

* iwffff_get_rom_header() gets the card directory wrong when opening
  the ROM file.

* iwffff_get_rom_header() forgets that the ROM header is padded to 512
  bytes length.

I also fixed some small stuff:

* Tried to improve snd_instr_iwffff_open_rom()'s doxygen comment. The
  commingling of file-system files (denoted by names) and ROM-embedded
  files (numbers) is somewhat confusing --- I'm still looking for the
  right words to explain it.

* Oh, and snd_instr_iwffff_open_rom() returns -EPERM for invalid
  bank/file values --- it means the wrong thing: ENOENT would be
  better.