From: Manuel Estrada Sainz <ranty@debian.org>

- undo recent change, made in the believe that "buffer" was the size of
  the whole file, it is just PAGE_SIZE in size.  This was causing kernel
  memory corruption.

  - Since files are allowed to have unknown sizes, by setting their
    size to 0, we can't preallocate a buffer of their size on open.

- Adapt request_firmware() to the sysfs change.

- Adapt drivers/pci/pci-sysfs.c to the sysfs change.