This patch makes the ROM reading code return an error to user space if
the size of the ROM read is equal to 0.

The patch also emits a warnings if the contents of the ROM are invalid,
and documents the effects of the "enable" file on ROM reading.
Signed-off-by: NTimothy S. Nelson <wayland@wayland.id.au>
Acked-by: NAlex Villacis-Lasso <a_villacis@palosanto.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>