Fix crash due to passing invalid r2x00dev->eeprom_file pointer to
release_firmware(). Since we copy eeprom data with EEPROM_SIZE
in rt2800_read_eeprom() we can use eeprom_file->size as marker
if the file was crated by request_firmware().
Acked-by: Kristian Evensen <kristian.evensen@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>