In order to allow other option roms to use these common
useful functions and definitions, this patch put them
in two new C header files called optrom.h and
optrom_fw_cfg.h. We also add useful out*() in*()
functions for different size, and new fw_cfg functions
to use when DMA feature is not available.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>