load a firmware file from the
char *filename, u_char
function loads a firmware from the file specified by
filename in the directory
/etc/firmware. Memory for the firmware is allocated
using malloc(9) with type M_DEVBUF as need be, within
a reasonable size limit.
If no longer needed, the firmware buffer buf can be freed using free(9) with type M_DEVBUF.
If successful, buf is set to point to the
allocation and buflen is set to the size of the
loadfirmware() returns 0. Otherwise,
it returns an errno style error.