The e1000 driver calls memory_region_add_coalescing but
kvm_coalesce_mmio_region is never called for those regions.  The bug
dates back to the introduction of the memory region API; to fix it,
delete and re-add coalesced MMIO ranges when building the FlatViews.

Because coalesced MMIO regions apply to all address spaces, the
has_coalesced_range flag has to be changed into an int.

Fixes: 093bc2cd ("Hierarchical memory region API")
Reported-by: Atsushi Nemoto <atsushi.nemoto@sord.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>