hw/usb/dev-mtp: Guard inotify usage with CONFIG_INOTIFY1

inotify_init1 usage was guarded by a check for linux but does not
exist on older distributions like CentOS 5 resulting in build
failures.

Signed-off-by: Matthew Fortune <matthew.fortune@imgtec.com>
Message-id: 6D39441BF12EF246A7ABCE6654B023536BB85D4A@hhmail02.hh.imgtec.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
