isapc: Fix non-KVM qemu boot (read/write memory for isapc BIOS)

isapc: Fix non-KVM qemu boot (read/write memory for isapc BIOS)

The isapc machine with seabios currently requires the BIOS region
to be read/write memory rather than read-only memory.

KVM currently cannot support the BIOS as a ROM region, but qemu
in non-KVM mode can. Based on this, isapc machine currently only
works with KVM.

To work-around this isapc issue, this change avoids marking the
BIOS as readonly for isapc.

This change also will allow KVM to start supporting ROM mode
via KVM_CAP_READONLY_MEM.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1369816047-16384-2-git-send-email-jordan.l.justen@intel.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>