memory: Refactor memory_region_clear_coalescing

Removing the update variable and quit earlier if the memory region has
no coalesced range.  This prepares for the next patch.

Fixes: 3ac7d43a6fbb5d4a3
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190820141328.10009-4-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed