Register a single area for vga bios and option roms

Register a single area for vga bios and option roms

Those guys are not different in nature. They're all roms,
not blessed with the graces of being written to. So there's
not need to issue multiple requests to memory registration areas:
just treat them as brothers, and put them all in the same
region.

It also has the nice side effect of improving the loading code
a little bit. Besides some of the ugliness going away, we're now
avoiding phys_ram_base dependencies in option rom code.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Paul Brook <paul@codesourcery.com>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7057 c046a42c-6fe2-441c-8c8c-71466251a162