Xapi_vm_migrate.migrate_send': simplify code
Xapi_vm_migrate.migrate_send': simplify code

to use map instead of filter_map - we always return Some (...), which is
equivalent to doing a map.

Signed-off-by: Gabor Igloi <7535f5501fd71876c93d896691e178fd3a11cfbb@citrix.com>

srowe/xen-api,srowe/xen-api,srowe/xen-api,srowe/xen-api,srowe/xen-api